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ABSTRACT \

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M. SC. JACQUES JALBERT Animal Science

ESTIMATION OF VOLUNTARY INTAKE OF HAY CROP SILAGE BY LACTATING DAIRY CATTLE

FED DIFFERENT LEVELS OF GRAIN

During the firat eighteen weeks after their respective calving .

date, three groups of fifteen Holstein cows with superior genetic

capacity (over 7500 kg of milk/305 days) .were Ifed respectively r high (H) (1 kg grain/2 kg FCM), a medium (M) (1 kg grain/3 kg FCM) and

a low (L) (1 kg grain/4 kg FCM) level of grain with hay crop silage as ~

the sole forage in a continuous lactation study. The average daily

consumption of wet (as-fed basis),. dry and NE1act haylage for group H,

M and L was: 23.2, 27.2 and 29.8 kg; 9.4, 10.6 and Il.1 kg; Il.7, 13.0 ..

and 13.2 Meal. There was a highly significant (P<.Ol) difference between

groups for wet hay1age intake, a significant (P<.lO) difference fpr dry

hay1age intake and no difference for hay1age energy intake. No

significant differences were foùnd in milk production. Dry matter content \

of the silage, metabolic weight of the cows and amount of grain consumèd

were found to be the best factors to explain the variation in either dry·

·2 2 haylage intake (R = 56.3) ~r haylage NE1act ~ntake (R = 73.1). No

differences in hea1th were found between the grôups; reproductive

performance was ~oorest for grou~ L, this group being energetica11y

underfed. rProduction functions have shown the importance of level of

grain wh~ haylage is fed. 1

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1

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RESUME

M. Sc. JACQUES JALBERT Sciences Animales

EVALUATION DE LA CONSOMMATIO~ VOLONTAIRE DE FOIN DEMI-SEC PAR DES VACHES LAITIERES RECEVANT DIFFERENTS N:rVEAUX DE CONCENTRES

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Pendant dix-huit semaines après 1eWi vêlage respectif, trois '"

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groupes de quinze vaches Holsteins d'un potentiel génétique supérieur .;: '.

(au-delà de 7500 kg de lait/30S jours) furen't respectivement placées

sur unération de grain haute (H) (1 kg grain/2 kg lait corrigé à 4%),

moyenne (M) (1/3) et basse (B) (1/4) comp1émentée de foin demi-sec à

volonté dans une étude de lactation continue. Les consommations moyenn~s

quotidiennes de foin demi-sec sur base humide, base sèche et base

d'énergie nette de lactation furent pour les groupes H, M et B: 23.2,

27.2 et 29.8 kg; 9.4, 10.6 et Il.1 kg; Il.7: 13.0 et 13.2 Mcal. Il y )

eut une différence hautement significative (P<.Ol) entre ~ groupes

pour la consommation de Join demi-sec sur base humide, une différence

significative (P<.lO~ -~ur base sèche et ,aucune différence sur base ,\/ -.

d~énergie nette de lactation. Aucune différence significative entre les \

groupes ne fut trouvée pour la production laitière. Le pourcentage de

mati~re sèche du foin demi-sec, le poids méta~olique des vaches et la \

quantité de gr~in consommee furent estimés être les facteurs qui eXPliürent

la plus grande proportion de~ v~riations dans la conso~tion de~,foin . 2 / ~'t /

dem!-seè, base sèche (R = 56.3) ?u base énergie nette de lactation ,\ ,/

(R~ = 73.1). Du point de vu~"'''ntét il n'y eut aucune différence entre

les groupes; aU,niveau de la reproduction, le groupe B montra les pires

r~sultats, ce groupe étant sous-alimenté énergétiquement. Les fonctions

de,production démon~rent l'impor~ance du niveau de concentrés quand du

foin demi-sec est utilisé.

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. ESTIMATION OF VOLUNTARY rNtAKE OF HAY CROP SILAGE

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If 1 BY LACTATING DAIRY CATTLE

'". FED DIFFERENT LEVELS OF GR4IN

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JACQUES JALBERT

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A thesis submitted tq the Faculty of Graduate Studies and Researcti in partial fulfilment

of. the requirements for the degree of 1

Master of Science

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Crampton Nutrition Laborator , .Department o~ Animal Science,

Macdonald Cqllege of ijcGil1 U ~ersity, Ste. Anne de Be1levu~, Quebec CANADA.' .' 1

• Jacques Jal bert 1978 , - ,"-~,. ____ I_.. .•

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March 1977

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Hay Crop Silage by Lactating airy Cattle èl

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ACKNOWLEDGEMENTS

Thfh author wishes to express- ~,r~cere thanks and ~ieat apP1\eciation

to Dr. Robert B. Harper of the Department of Animal Science, Macdonald

College, for originatihg the projectt and for his supervision and i .

invaluable ad~ice during aonduct of the r~search.

Special acknow1edgement is 'due to different people and of

people: Mr. Rudi Dal1enbach, Director, Macdonald College Fa and his

St~ff; Dr. John E. Moxley, Department of Animal Science

Dairy Herd Analysis Service (DRAS), a~d ?iS Staff; Miss Denise\Gaulin and

Mr. Bruno Dolgowicz from the Crampton Nutrition Laboratory.

Appreciation is extended to Dr. B.W. Kennedy for his help, suggestions 1

and comments on the statistica1 analyses.

The patience, encôurage~ent and collaboration of my wife, Maureen,

throughout the past three yeats are fully acknowledged. ,

Finally, the author wishes to express his appreciation to the

Macdonald College and the Quebec Agricultural Research and Services

Counci1 for their financial assistance.,

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• TABLE Q.F CONTENTS

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ACKNOWLEDG~NTS t ••••••••••••••• ., ••••••••••• ~ •••••••••••••••••• '

LIST OF TABLES ... " .......................................... . - LIST OF FIGURES ............................................ , ...

Chapter

, 1. INTRODUCTION . ............ " ........................... . II. REVIEW OF LITERATURE •••••••••••••••••••••••••••••••••••

, \ A. GENERAL ASPECTS 1 IN RELATION TO FOOD INTAKE

B.

c.

REGULATION •..• '" ••...• 1 •• ' ••••••••••••• " ••••••••••••••

1. Introduction ....... 1 • •••••••••••••••••••••••••••••

2. Physiologieal' factors ••••••••••••••.••••.•..•.•

3.

4.

a. Ch~ostatic regulation ••••••• ' •••••••••••••• b. Thermos ta tic regula tion ••...•.•••••••••.••• c. Lipostatic regulation •••..••••....•.••..••. Physic"'al factors ................. 111 ••••••••••••••

a. Reticulorumen and lower tract regulation ••• b. Calorie density regulation ••••• ',' .~ ••••••• Pa1atability as a regulation factor .•••••• '.' •••

RELATIVE IMPORTANCE OF INTAKE AND NUTRITIVE VALUE IN DETERMINING FEEDING VALUE •••••••• ~ •••••••••

, PREDICTING PEED INTAKE FOR LACTATING DAIRY COWS ••••• 1. 2.

1 Introduc tion ........ ............. ~ ............. . Cow characteristics. t." •.••.•......•...•.•..•.• a. b. c. d.

Body weight and intake in lactating cows •• ~ Body weight change and intake •••••••••••••• Age and intake in lactating cowa ••••••.••••

c Mi1k production or stage of lactation and intake .................... t ..•••.....•.

e. Requirement versus consumption ••••••••••••• ~. The fat cow and post calving intake.", ,\ •••• g. pregnancy and intake ••••••••••••••••••••••• h. Heritabi1ity and intake •••••••••••••••••••• i. Individuality and intake ••••••••••••• '.'~'"

vi

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ix

1

3

3 3 4 4 5 5 6 6 8 9

10

12' 12 .!2

'12 13, 14

15 16 17 18 18 19

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,1/ Table of Contents ~Contld)

Ration char~cteristicB and intake •••••.•••••.•• 1 a. Forage character~stics •••••.•••••••..••.•..•

i. Dry ma~t~ content and intake ••.•••••••• ii. Texture and intake ••••.••••••••••••••••• iii.pH, organic acids and bases'and the

intake of hay crop siIage ••••••••••••••• iv. Digestibilityand chemical composition •. v. Protein content and intake "' ••••••••••••• vi. Intake of hay crop silage when fed

alone or wi tb bay •••••••••• ~ ••••••••.•.• b. Concerttrate characteristics. r •••••••••••••••

"1. Texture ........ . 1 ••••••••••••••••••••••••

i1. Simple or complex mixture ••••••••••••••• iii.Level or amount of concentrate ••••••••••

c. Complete rations cbaracteristics ••••••••••.• i. Diges tibili ty •••••••••.••••••.•••••••••. ii. Calorie density •.••••.•••••••••••••••.•• iii.Ration balance." ........................ . iVe Blended feeding ••••••••..••••.••.• ' ••••.•

4. ) Envlrorunental characteristics ••.•••••.•••••••••• a. Climatic effects .•..•.•••...••••••••••••••.. b. Sbortage of water .......................... .

5. Predictive equatio~s •• " ............... , ••••••••• a. Equations predicing DMI based on ration

only ......................................... . b. Equations predicting DM! based on cow

s tatuB only ................................ . c. Equations predicting DM! based on rations

and cow characteristics ••.•••••••••••••••••• d. Linked to least cast formulation •••.•••••.•• ,

\ OBJECT OF RESEARCH ••••••••••••••••• ~ ................. ~ ••••

l ' EXPERM'N'rAL. • .. • . . . • . • • . . • • • • . . • . • • • • • • • . • • • . Il •••••••••••

A •• GENERAL PROCEQURES ••••••••••••••••••••••••••••••• ~ ••• l~ Introduction .......... , ....•......... . " . ......... . 2. Experimental design •...•.••••..••.•••...••••..•• 3 • COW8 •........... ., •• ., •• " ••••••••••• : •••••••••••• ; ' •••

4. Hay crop silage ............................•..... 5. Grain mixture ............... J ..... '. ~ ............... . _6.. Milk sampling .......... : ..................••.....

7. a.

a. Fat percentage determinatibn •••••••••••••••• b. Protein percentage determina~ion •••• , ••••••• Sampling and 'stor~ge technique'-" .l.: ............ . Chemical analysis ............. ~ ......•..........

-if a.' Dry matter ............... ...................... . b. pH determination ............................. . c. Nitrogen and protein determinations ........ ..

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:P'age

19 20 'II

20 22

23 24 26 l

27 28 28 28 29 30 30 31 32 32 33 33 34 34

35

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Table of Contents (Cont'd)

Chapter

IV. A. 8. c. i~ Crude protein •...•••...•••••.•.•••...

Pfge

50 51 51 51 51

, v.

B-.

9.

10. 11.

12.

ii. Acid detergent nitrogen •.• ~ ....••.... ii1. Digestible protein (DP) •...•...•••...

d. Fiber analysis ......•......••••...•••.... i. Neutral detergent fiber (NDF) ..•• '.' .• ii. Acid detergent fiber (AnF) and aeid

detergent 1ignin (ADL) ..•• '.' ..••••... i1i. Hemieel1u1ose ....••.•..•••.•.•••..... iv. Cellulose .... , ...................... .

e. Nutritive value index (NVI) ••••..•••..... f. MineraIs determinations •••.••••..•••••... Extrapolation of the NE

I values ••..•.••..••

aet Fat corrected mi1k (FCM) values .••••••.• ~ •...

-; Evalua tion of the requirements of the lactating cows .............................. . Statistical analysis ••.••••••••••••••••••••••

1 EXPERlMENT 1. Introduction ................................ . 2. Experimental results •...•••••••.•••••••••••.

a. Hay.crop silage composition .•••••••••••• b. Grain 'composition .••••••.•.••••••.•.••.. c. Cow characteristics .•••.••.•••••••..•••. d. Group characteristics ••••..•.••••.•••••.

3. Analysie and 4iscussion ••••••••.••••.••••••• a. ,;Group and parity effects

i. Wet haylage intake •.••.••••••.•••••. H. \Dry haylage intàke ................ .. iii.Calculated haylage NE intake •.• : •.•. iVe Fat-correct milk production •••••••••

-b. Raylage Intake and correlation with Haylage components ••.•••••••••••••.•••••

e. jtegression ana1ysis •••••••.•••••.••••••• i. Wet haylage ,intake •••••••••••••••••• 11. Dry haylage intake •••••••••••••••••• iil.Calculated haylage NE intake •.••••••

d. Requirement versus intake •••••••• · ••••••• e. Health and reproduction ••••••••••••• ' •••• ' f. ~ Economie aspee ta ............ " .......... .

\ . S~Y :AND CONCLUSIONS •••••••• r •.•••••••••••••••.• -" .

52 52 52 052 53 53

54

54 55

56 56 56 59 63 63 70 70 70 71 72 73

74 76 76 77 79 -80 88 91

95

LITERATUR.E OITED ••••••••••• l, •••••••• ',.' t' •••••• • '''. • • • • • 97

APPENDIX TABLES ••••••••••••••••••••• Il" • • • • • • • • • • • • • • • • A-l

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LIST OF TABLES

Table Page

1

1. Cow and heffer .ratings and their distribution

2.

3.

4 .

5.

6.

7.

8.

9.

10.

IL

12.

13.

14.

15.

16.

17.

18.

19. ,

20;

21.

between the three grou.ps.............................. 46

Physical composition of the grain mixes ••.••••••..••••

Forage characteristics ••.••..••••...•.•••..•.•••..•... ~

Simple correlation betweJn hay crop si1sge components.

Grain charac&eristics ..••••.•••.•...•.••....•••..... :.

Simple correlations hetween tiKe grain components ••.•••

Overall me ans of the raw experiment~l data............ -

Average dry'matter intake (DMI)(kg/day) and body we1ght (kg) over the 18 week period ••••••.••••••....••

Least square estifuates for wet haylage intake (kg/day) (±SD) ..••••••..•••••.•••••••••••.••..••••...•.•••..••.

Least square estimates for dry haylage intake (kg/day)

Least square estimatesLfor calculated haylage NE-intake (Mcal/day) (±SD) ••••••••••••••••••••.•••.••.•••

Leasç square estimates for fat-eorrected milk (FCM) (kg 1 day) (±SD) •.••••.•...••.••.••••••.•••..•.•••

Simple correlation between average haylage DMI, average grain DM! and haylage components ••••••••••.•••

Regression on wet hay1age intake (Y) (kg/day) •••••.•••

Regression on dry hay1age intake (Y) (kg/day) •••••••••

Regression on hayla~e NE intake (Y) (Meal/day) ••••.•••

Pattern of body weight changes •••••••••••••••••••••••• {

Intake and calorie density •••••••• , •••••••••••••• ~ ••••

Health status .......... ; .......................... i. •••• .. Reproduc tive statua ................................... .

Input-output charaeteristics based on 305 d~s ••••••••

ix

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58

60

61

62

63

71

72

73

73

75

76

77

79

81

86

89

91

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Figure

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LIST OF FIGURES

Effect of week of lactation on, grain, haylage and total dry matter intake, and body weight. Grou pH. • • • • • • . • • • ..•• , • • • • . . . • . • . . . • • • . .. . .. . • . • • . . . • ..

2. Effect of week of lactation on grain, haylage and total dry matter intake, and body weight. Group M ................................................................................. ..

1

3. Effect of week of lactation on grain, haylage and total dry matter intake, and body weight.

66 !

Group L •.......••....••••.........•...........•. ~ • . . . 67

4.

5.

6.

7.

8.

9.

• 1

Milk production curves ••••.......•.•..••...••••••...•

Effect of week of lactati",n on net energy required, net energy 1 consumed and body weigh1t. Gro~p M .............................................................................. la- ... ..

Effect of week of lactation on net energy ~ required, net energy consumed and body weight. Group L ....................... . ~ ........................................ .

Effect of the total ration NE on the total dry matter intake ........................... If' ................. ..

1 ~

Response in tOFe with mi1k at $10.00/45.4 kg FCM •••••

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1. INTRODUCTION

During the last decade more emphasis has been put on the

estimation of voluntary intake sinee it has been recognized that it

contributes about 50% 70% of the forage nutritive val

Each year, more and more forages, such as hay, hay

silage and corn silage are fed ad libitum alone or in combi

various levels of grain depending on the productibn criteria. It is • therefore becoming quite difficult to evaluate the forage consumption

of individual lactating eows. These faets lead to serious problems

when assessing appropriate grain recommendations based on the different

inputs suitable for milk production.

~ In the last few years, alfalfa production in the Province of

Quebec has shown a more than ten-fold increase. Produced alone or in

combination with timoth~ hay and/or bromegrass, it is often harvested

as a hay crop silage, due to the easy mechanization involved in

harvesting such a crop and to the improvement in nutritive value gained

by doing so.

During the past few years, the priees of grain .and protein

supplements have ehanged quite often. The price pa id for milk also has

been changing due to a previous period of underproduction followed now

by period of overproduction. It is therefore quite impor;pnt to

investigate the factors influencing the production functions an4 the

margina! rates of substitution ~n relation to priee fluct~ations to

achieve in either lesst-cost or maximum-profit situations.

Finally, controversy has arisen regarding the health and •

reproductive status of herds fed mainly on ensiled forages without

hay since these techniques have been suggested.

For a better understanding of chemical composition of forages l

and grain mixtures, some new analyses have been presented recently,

which more closely reflect their biochemical composition.

The~fore, the purpose of this research is to study the

vOlunta~~consumPtion,of hay crop silage fed ad libitum to lactating

dairy cattle fed three levels of grain. Also, some emphasis is given

to relations with chemical composition of the feeds, ta the health

and reproductive status and finally to the economical feasibility of

2

such a system, involving dairy eattle with a superior genetie potent1al

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(over 7500 kg of milk on a 305 day basis).

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II. REVIEW OF LITERATURE

A. GENERAL ASPECTS IN RELATION TO FOOD INTAKE REGULATION.

1. Introduction

Baumgardt (1969) described feed intake as a homeostatic mechanism fr~'

defined as the "self-regulating negative feedback systems which serve

to main tain the constancy of the internaI environment" or more simply

as the tendency of ~n organism to maintain a uniform and beneficial

physiological stability within and among its parts.

Baile and Forbes (1974) concluded that the effects of varying the

energy requirements of the animal by changing its output of heat.

deposition of body tissue, or yield of milk and the effects of varying

the concentration of avai1able energy in the diet show that. in general,

ruminants tend to maintain a constant energy balance by changing feed

intake in proportion to their altered physio1ogical and environmental

circumstances.

COhtrol of energy balance and especially of teed intake is closely

associated with the'function of the central nervous system, i.e. the

hypothalamus of the diencephalon which is the region of the brain most

directly concerned with the control of feeding (Bai~e and Mayer, 1970).

In ruminants the bu1ky an~ fibrous nature of the foods normally

eaten and the1r low content of digestible energy lend emphasis to the ,.

importance of the physical effect of distension of the gut in limiting

voluntary intake (Campling, "1970).

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Palatability which is, essentLally, a summatlon of many

different factors senses by the animal, representing stimulation

derived from sight, amell, touch and taste as affected by physica1

and chemical factors, aIl of which may be modified by physiologieal or

psychological differences in individual animaIs (Goatcher and Church,

1970) also has some effects on f~od intake regulati&n.

The reader must be cautioned that this section does no: present

a complete literature review of the subjeet but intends to point out

sorne aspects that will be useful in an attempt to understand the

physical and physiological factors involved in the explanation of the

results of this trial •

. For a more complete investigation, the reader ia referred to

Baile and Mayer (1969), Waldo (1970), Hang (1970), Baumgardt (1970a),

Baile (1971), Bull (1972), Jones (1972), and Baile and Forbea (1974).

2. Physiologieal factors

The different pathways r,elating food intake with the regulating

eenter are sometimes eonfusing; some of 'these will be presented.

a. Chemostatic regulation

Mayer (1955) wae one of the firet to suggest this theory. !

.~ver" aval1able data indicate that blood glucos~ and insu lin do 1

not change appreciably when animaIs are fed as reviewed by Chureh

et.!!.. (1971).

A~é~ate, propionate, and butyr~te are produced in large 1

quantities by the rumen microflora, abeorbed through the rumen wall, , \

and used as energy substrates in most tissues of the ruminant; they

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5

~~hus supplant glucose and long-chain fatty acids as major sources of

energy. The rates of production of one or more VFA might influence

the size of individual mea1s by the peripheral mechanisms, but are

unlike1y to play a major role in the regulation of energy balance

(Baile and Forhes, 1974).

b. Thermostatic regulation

Balch and Camp1ing (1962) have suggested that there may he some

thermostatic control of feed 1ntake. This theory states that eating

is a response to a fall in heat production and that the stopping of

e~ting 1s a response to a rise in heat production (B1axter, 1962).

However, the thermostatic regulation of feed intake in ruminants 1s a

response to environmental temperature rather than to heat of metabolism

of feed nutrients (Jones, 1972).

c. Lipostat1c regulation

Various theories have been put forth suggesting that the amount

of body adipose tissue may serve to activate a féedback mechani,sm which

would serve as a long-term control over ~ppetite (Balch and Campl~ng,

1962). However, there 18 little ev1dence to support or refute this

theory, a1though it seems plausible (Church et al., 1971).

A1though ltmited information is avai1able on the effeets of the 1

cDmbined physiologieal factors in relation to food intake, Russek

(1976) reeently formulated an equation which cqmbines several

physio1ogieal components, i.e. glycogen~static, thermostatic glueo-

static, 1ipostatic and osmostatic eomponents, to express the inf1uepce

"Of each factor in the simplest mathematical way.'

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3. Physical factors

Ample evidence from many different research reports exists ta

show that consumption of roughage by ruminants is reduced when the

quality of the roughage is 1ow. There ~ve been different experiments

carried out in various laboratories in an.attempt to determine what

the limiting factors may be (Church ~ al., 1971).

à. Reticulbrumen and lower tract regulation

Evidence that voluntary food intake is limited by physica1

conditions within the gut and particularly by the amount of digesta

in the!reticulor~en has arise,n in several ways. These are: (1) the

effects on voluntary intake of intraruminal additions or removal of

food and other materials and the dilution of food with inert materia1; , (II) the re1ationship between rumeni fi11 and vo1untary intake; and

(III) the relationship between the rate of disappearance of digesta

and voluntary intake (Campling, 1970).

A generalization often e'ncountered (U1yatt, 1973) is that when

offered herbage the ruminant eats to a certain distension of its rumen

and that the time taken to reduc~ this rumen load ta the point'where

hunger recurs would depend on the rate of breakdown of the feed and the

rate of passage of undigested feed residues out of the rumen (Cràmpton 1

~ .al., 1960).

\ 1 / Van Soest (1965a) concluded that the relationship betwJen '

digestible dry matter and v01untary Intake depends on the proportion

of digestible energy from cell-wall'constituents. These findings were ,

consistent with the theory that fiber mass inhibi~s intake in those . , \

forages with a high cell-wall content. The total fibrous part of

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legumes, represented by cell-wall constituents, does not appear to

be large enough to inhi~it intake. The point at(whiCh fiber mass

appeârs to become limiting occurs when cell-wa11 content lies between

50 and 60%'of the forage dry matter.

According to Waldo (1970), the generalized concept of ruminants

7

• consuming more energy as ration digestibility increases until their " , ;

"requirement" ;ls met seems valid.

B1.xter'.t al. (1961, 1962, 1966) observed an increase in i~ake of forageS as digestibility increased. However, their data do not show

<" intake to be related to '~igestibility in quite the same manner as

Conrad et al. (1964). Blaxter et al. (1961, 1962, 1966) consider the

limiting,mechanism tp be total tract fill relative to wa while

Conrad et al. (1964) considered it to ~e fecal organic matter output

1 W1.0 re ative to • B1axter's rations were grass while Conrad 1 s were

'-./ mi~ed rations containing much legume forage (Waldo, 1970).

Conrad (1966) indicated that at low digestibilities (52-66%) ,

the lev~~ of milk production was determined by the animal capacity, .. ~

and the rate at which undigested feed eould be moved through the

alimentary canal. At high levets of digestibil1ty (67-80%) the .. 1 (

physiologieal state of the cow wàs the primary determinant of feed

'intake. The partieular point a~ong a series of increasing digestion

coefficients a~ whieh physical limitations on eating capacity

vanish and the influence of production becomes dominant varies with

the body size, production and fecal excretion rate.

Waldo (1969) presented a method for calculation of rates of

passage and digestion. He suspected that the fiber mass i8 the major

additional factor governing intake and that this should be considered i

when forages are substituted for concentrates in the ruminant ration.

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b. 'Caloric'density regulation

Baumgardt f1970a) proposed the concept of calorie density

(kcal/ml) as a tentative model for integration of the changes in

importlance of physical and physiological factors. He mentioned

that his main goal with this new concept ià to assess the

quantitative relationship betreen nutritive value of t~e food and

intake so that feed and energy intake could be accurately predicted

from some property of the ration which could be readily measured.

Baumga!dt (1970b) looked for easily measured properties of rations

which would accurately predict feed and energy intake. Density was . ~

selected on the assumption that, at a given level of digestibility,

a feed with a higher density will have: (1) a more rapid rate of \

8

digestion; (2) a more rapid rate of passage; and (3) occupy' less space

in the digestive tra~t per unit weight. Density coupled with a "

measure of digestibility should provide a mo~e accurate ind~x of the

fill-producing ch~fracteristics of a ration than would either factor

alone. i

Bull (1972) presented th~ results of severai experiments with ~

complete feeds in which intake has been measured in lactating cows 1

• 1

fed diets of varying digestibilities. He concluded that under

production conditions included in those studies, calorie concentrations

of about 2.5 kcai DE/gm. DM, or ~ore, resulted i~ constant intake. \ \

Bull et ~. (1976) fed complete mixed diets of alfalfa hay and

concentrate to Holstein cows in a series of periods to determine the , 1 1

relationship between calorie density (Meal digestible energy/liter) ~ 1 .

of th~ diet and energy intake. The diet with calorie density of

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9

·68 Meal/liter represented the point above which physiologiea! 1

Tegulation was e~ployed by the an;mals. They coneluded that th~s l,

, 10

concept can be used to formulate ~~ets whieh maxtmize the util~za­~/

tion of forages by keeping the DE density close to that point where

phY$ieal and physiologieal factors converge in the regulation of

energy intake. \

4. Palatabi1ity as a regulation factor

Definitions of pa1atabi1ity seem to differ aecording to the

author, but one which May be adequate might be the relish whieh an', 1 1

animal shows when eonsuming any given feedstuff or Tation (Chureh et al.,

1971).

After an lintensive' literature review on this topie, Marten 1

(1970) observed that because of the lack of documentation on the real

significance of palatibility dUferences in many forage studies, it

ia difficult ta make any general statement Tegarding the importance

of forage pa1atability. Once one leaves the rea1m of situations in

whieh the animal has a choice, there is re1ative1y little concrete

ev~de~ee that the measurement of pa1atability is of more th an aeademic

, ,significance. The evidence ~i1able indicates that usua11y no

association exists between di~estibility and palatability. There is

a signifieant amo~ of eonf1icting opinions and researeh evidenc~.

regarding the association of forage palatability and either vo1untary

intake or animal performance. \

Coppock e~ al. ~~~74a) condueted three expertments to s:udy J

f the magnitude of variat~rt and eonsistency of forage

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'dairy cattle. The conclusion àf their tri~lent support to the rationale

of more emphasis on blended complete feeds whenever (1) more than one

forage is fed; (2) when the forages differ greatly in their nutrient

content because when they are fed separately large differences exist in

forage preference within the dairy cattle population.

B. RELATIVE IMPORTANCE OF INTAKE AND NUTRITIVE VALUE IN DETERMINING FEEDING\ VALUE.

Ulyatt (1973) defined nutritive value as the concentration of

nutrients in the herbage, or as the anima~ production response per unit

of food consumed, whereas the herbage feeding value is defined ~s a \

biological assessment of the worth of a'herbage in terme of animal

production. It is the animal production potential of the herb~ge under a ~

given set of environmental circumstances."

Raymond (1969) introducing his intensive literature review o~ "r .

the nutritive value of forage cr~ps m~ntioned that the nutritive value of

forage crops should not be consideted as a single parameter, but composed " " \

of a complex of parameters that determine the nutrient intake of ruminant

animaIs fed on that forage. In this it is different from the classical

concept of nutritive value, as a feed concentration (TDN or, net energy) ,- , \

by includirts, feed \intake as an Integral component of nutritive value.

He~y (l970b) suggested that ,the concept is now accepted of

\ ' combining digestibility and intake into a single index to provide a

1 mean~ of e ~luati~g the feedin~value of forages more effectively than

\ \

any method p eviously.used.· In practice it makes little difference whether

the index used is the Nutritive Value Index (NVI) proposed by Crampton

(1960), ~r ~aily Digestible Energy Intakè (DEI), expressed as

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11

0.75 kcal/W (Heany ~ al., 1966).

Donefer (1970) reviewing the work done st Macdonald College

mentioned that the NVI calculation was designed ta obtain a sin~le value

which might best describe the contribution of a forage in meeting animaIs'

digestible energy requirements. Whereas NVI represents a relative

measure useful in the comparison of different forages, the same criteria

invo1ved in its calculation can a1so be useqrto express the abso1ute

digestible energy intske potentia1 of a forage in terms of kcal DE/kg w· 75 •

It Is difficult to resolve the relative importance of voluntary

intake and nutritive value in determinlng feeding value because the two

parameters are correlated, nutritive value being a producd.on response per

unit of intake (U1yatt, 1973). Crampton et al. (1960) indicated that

relative intake accounted for 70% and digestibility 30% of their nutritive

value index. Corbett (1969) concluded tbat 60-75% of the variation of

DEI could be accounted for by variation in intake.

Heany et al. (196B) pointed out a further prob1em with such analyses,

name1y, that there is a large disparity in the accuracy with which intake

artd digestibility (or nutritive value) can be measured. The coefficient

\ of variation of voluntary intaké is approximately 2.5 times greater than

tbat of digestibility and this may 1esd ta the relative importance of ,

intake being overestimated.

Howeyer, Heany (1970a), after the study of pure forage~ and mixtures,

concluded th~t whatever the relative merits of intake and digestibility \

for forage eva1uation and regardless of which one has the major influence

1 on the feeding value of a given species, neither intake rtor digestibility

can reliably be used separately to make between species comparisons or

evaluate forage mixtures. For such comparisons it ts essentia1 ta use an

index, .like DEI, which combines both factors. However no results of

'\ \

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( 12

experiments with lactating dairy cattle support this theory.

C. PREDICTING FEED INTAKE FOR LACTATING DAIRY COWS

1. Introduction

Although the the feed intake regulation are

beçoming more weIl understo persist in the

evaluation of the voluntary the lactating dairy eow. Ret

physiologieal status, that she produces, makes her respond

differently than the other animaIs. 1

The total amount of food eaten by the lactating dairy eow in a

given period of time depends on (1) the number of meals eaten in that time;

(,2) the length of each Meal and (3) the rate of eating during each meal

(Bines,1976). Changes in any of these,three factors or any combination

of these affect the intake.

Factors influencing intake may be broadly categorized as b~ing due .. to characteristîcs of the cow, the ration br the environmend. Following

is a discussion of these headings and a look at several published equations

f" 1 aiming at the prediction of food intake and their use in the field of the

dairy eow nutrition.

2. Cow characteristics

Following is a discussion on several characterist1cs known to have ~ 1

an influence on feed intake in lactating cattle.

&. Body weight and intake in lactating cows

Intake is commonly expressed in terms of body weight (BW) or \,

\ 75 metabolic body size (mairtly BW' ) (MW).

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13

Johnson ~ al. (1966) réported no relationship bet~~en forage DM

intake and HW or forage DM intake and MW in lactating cows.

Curran et al. (1970) found neither BW or MW significant in aIl of

their models and in aIl sets of data. They were therefore complete1y 1 .

ineffective variables for accounting for differences in intake between

cows in these sets of data.

However, Journet (1969) indicates a correlation coefficient of

0.3 to 0.5. \ 1

AIso he reports an increased consumption of 0.8-1.2 kg

o~ta1 dry matter/day for each 100 kg HW incr,ease. Remond et al. (1973)

reports an increas~d consumption of 0.9 kg/day of the forage component

of the ration for each increase of_ 100 kg of BW. Mather et al. (1960)

report an increase in forage dry matter consumption of 1.02±O.25 lb.

per hundredweight increase in body weight • •

McCu110ugh (1959) in a review mentions that the correlation

coefficient between intake and BW ranges from .390 to .980.

Coppock et al. (1974b) found a mean dry matter consumption per ~

lactation of 3.5% of body weight for one of their groups of cows fed a

comp1e~e ration. Previous studies had reported lower intakes. '

Mather et al. (1960) mentioned that the simple ratio (DM/BW)' 'tends

to give a false picture of the relationship between size and intake and

that-the true relationship 18 probably curv{linear.'

Conrad ~~. (1964) reported a relationsh~p of total DM int~ke and

BW for rat~ons having a digestibility of 52-66% and a relationship with

-MW for the ration having a higher digestibility (67-80%).

b. Body weight change and Intake

Curran et al. (~970)_ fQund l~veweight change ta be a significant

variable in aIl models pr~dicting DM intake during weeks 1 to 4. It

,1

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14

marginally failed to be significant in weeks 5 to 8, and in weeks 9 to l,

12 and 13 to 16 it became p,rogressively less significant.

Monteiro (1972) proposed a closed-1oop system in which an expression

is deduced relating the response of food intake to changes in milk yield .' and b~dy weight gain.

A closed-loop system necessari1y involves a de1ay in the response

to changes in production. The rate of increase of food intake is

therefore slower than the rate of increase in mi1k yield. The consequent

deficit in energy during the rising part of the 1actation~curve isrnet

by the mobilization of body reserves, which are partly accounted for by

los ses in body.weight. During the declining part of the lactation the

delay effect 1eads to an excess of energy intake and to the replacement

of body reserves and, consequently, of body weight.

c. Age and intake in lactating cows

Age is reported as being a non-significant term in aIl sets of data

in the etudies of Curratt ~ al. (1964), as well as for Johnson et al.

(1966) •

According to Journet (1969), age is relatively unimportant after 1:

we account for the, gain in weight between the first lactation and the , ~

subsequent ones.

However, Remond et al. ('1973) reported an intrinsic increase in

voluntary consumption comparing first-ca1f heifera and older cows. The

increase averages 100g of forage DM consumed ;;per day for the secotid

lactation cow over the first-calf heifer.

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Milk production or stage of lactation and intake

In general, there is a distinct la~ in the response of food

intake to the increased energy demand of lactation. Thus, in ear1y

lactation, the dairy cow is commonly seen to lose a considerable amount

of body weight whiçh is replaced at a later phase of lactation when mi1k

yie1d starts to fall while appetite remains high. According to Bines

(1976), it appears that the lag between peak yield and peak intake is

greater in the first lactation (over 8 weeks) than in subsequent

lactations (only 4 weeks). According to the same author, the increase

in intake from the time of calving ta the time of peak lactation is of

-the order of 30-40 percent. Journet (1969) presents a wider range of

figures varying from a 15% to a 5070 increase. During the second part of

the lactation a decrease of 15-17% of peak intake seems to be usua1 with

a ration based on good qua1ity forage.

Re1ating the milk yield, as fat-corrected milk (FCM) , to forage

DM intake, Johnson ~ al. (1966) found an important association. The

2 correlation between these two factors was .59, with a R of 0.35. This

15

means that rough1y one-third of the variation in DM intake was associated

with a variation in FCM production. For every increase in production of

1 kg of FeM, he found an increase in forage DM ~ntake of 220 g. Bines

(1976) found the same re1ationship but to a 1esser degr~e; the increase

of DM intake was 100 g. Remond et al. (1973) showed the same kind of

re1ationship with an inctease in total DM intake of 303g.

Looking at the reverse re1ationship, Johnson et aL (1966)

computed an increase of 1. 6 kg of FCM for every kg increase in voluntary

forag'e consumption.

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-Curran et al. (1970) rep~rted that at given leve1 of concentrate,

/ milk yie1d was positive1y associated with feed intake. In their ,

analyses they a1so indicated that the significance of tlJ.e milk yield

term was not entirely due ta correlations with concentrate feeding since

~ both terms had significant partial regression coefficients when included

in the same mode1s.

In the study of Conrad et al. (1964), milk production is limited

by DM intake when the ration digestibility is below 66% and milk

production drives DM intake when thé ration digestibility ls over 67%.

In his close-loop system, M'Onteiro (1972) assumed that milk

production behaves as an independent variable which gives a 'command

signal' to t~e control system.

McCullough (1959) reviewing the subject showed correlations of

16

.660 and .638 between the leve1 of produc tion and the level of dry t1Ja tter

intake. However he added that the increase in dry matter consumption

with increasing production is not easi1y demonstrated. The high coeffic-

ients of variabi1ity between cows frequently result in average intakes

which show no relationship between intake and milk production.

e. Requirement versus consumption

Few studies accurately show the pattern of the energy requirement \ '

in relation to the energy yo1untari1y consumed. te is however quite

important to know ta what extent the cow really can adjust ~er consumption

to her needs.

Murdock and Hodgson (1969) comparing aHaHa hay with high-moisture

grass silage plus hay found, as expected, tpat none of the rations ~

supplied the estimated TON requirements recommended by NRC in early

"

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lactation. :'The intersects of the requirement and consumption Unes

indic~te TDN consumption equalled requirements for both roughage rations

at about 82 days postpartum. Alter that they consumed more energy than

their~actual requirement, but at the end of the lactation they had just

regained the weight they had lost at the/beginning.

Coppock et al. (1974b) comparing several forage-concentrate

rations based on corn silage and alfa1fa-grass silage founcl cows in

the latter stages of lactation did not appear to regulate their intake

according to physiologieal requirements for milk production.

Everson et al. (l?76) 100king at constant or variable forage-to­I

17

grain ratios in complete rations have shown the advantage of the variable

ratios in which the cows had a more positive energy balance during early

lactation, 10st less body weight, showed an earlier postcalvihg estrus,

recovered lost postpartum weight faster, had higher blood glucose

and lower ketone values.

This study shows how that changes in the ration during the

lactation are beneficial when considering the inability of the cow to

rea11y evaluate her needs or adapt her ingestion to a lower digestibility

ration.

f. The fat cow and post' calving intake

There ia now evidence that fatness reduces intake in cattle

(Bines, 1976). The thin animal perhaps has a requirement for nutrienta

for .fat synthesis which is reduced or absent in the fat cow.

Also, extensive deposition of fat within the abdominal cavity

apparently reduces' the effective capacity of the cavlty and this la '

asaociated with a reduced roughage intake by ~hese animaIs (Bines, 1971).

This condition often leads to what is called the 'fat cow syndrome'.

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g. Pregnancy and intake.

. According to Bines (1976), two opposing effects influence food

intake during pregnancy. The increased demand for nutrients for

deve10pment of the fetus tends to cause intake to rise. Towar~~ the

end of pregnancy however. as the fetus increases rapidly in size, the

effective volume of the abdominal cavity for expansion of the rumen

during feeding is reduced and this will depress !ntake relative to ~and

particular1y if the concentration of the ration is low.

However, Johnson et al. (1966) concluded from their study that

suggestions of increased appetite accompanying pregnancy in dairy

catt1e are entire1y unfdunded.

Monteiro (1972) reminded us that the rumert volume in 1actating

cows ia 32-40% larger than in dry cows.

h. Heritability and intake'

Miller et al. (1972) found heritabilities of intake of ~orage,

grain and total'net energy of 0.19, 0.26 and 0.42 respective1y in cows 1

given hay and silage ad libitum wit~ concentrates fed according to

production.

Johnson et al. (1966) found that t~e repeatability of forage DM ~

intake between the 1actablon and dry periods was high Cr = 0.73). ,... Journet (1969) noted a range of coefficients of repeatability of

" 0.22-0.34 for between lactation and 0.55-0.85 for within lactation dry

matter itttake. ""

According to Stone et al. (1960). on a withln forage treatment

period and year'basis the repeatability of the week1y average of forage

dry matter consumption was 0.70.

o

1 19

i. Individuality and intake

As far as we can look in the 1iterature, this factor bas a1ways

been widely recognized. Although its llnportance is relatively

decreasing as we understand more adequately the factors which influence

the dry matter intake, it is still the most important single factor.

Johnson ~ al. (1966) cqncluded that it is apparent that highly

significant differences existed among individual cows with respect to

forage appetite, as measured by forage DM intake.

McCullough (1959) reported that difference in intake secondarily

reflects small differences in size and differences in production, but

primarily reflects inherent differences between cows of simi1ar size

and production.

Van Soest (1965a) added that when considering the problem of

comparing voluntary intake with chemical composition, expected

relationships are more difficult to rationalize because the individuality

of the animal plays a larger role.

Finally, as expressed in II-A-4.,

complete ration whenever i:t is possible to

preference by dairy çattle.

3. Ration characteristics and intake

After the animal itse1f the ration is evidently the most important

factor. We will look suc~essively at the components!of the forage, the

concentrate and the èomplete ration. \

(

20

a .• Forage character1stics

i. Dry matter content and intake

Journet (1969) reported a'20% decrease 1n consumption of grass- ~

legume direct-eut si1age (20% DM) when compared to hay harvested in

good condition. W'ilting increases consumptian ta a leve1 where

haylage (50% DM) is consumed at the same level as the corresponding hay.

Demarquilly (l973) studying'the changes b~tween ensiled material 1\"

and the initial green forage showed that ensiling caused a large (33%

on average) and quite variable (from 1.0 to 63.8%) reduction in the

vo1untary intake of the forages. This decrease did\ not depend much

upon the'. treatment applied except for wilting. For example there was a

decrease of about 35% for unwilted silages with or without additive

and 27% for wilted silages.

Jar~ige et al. (1974) reminded us that the consumption decreasè

\ " is not related to the water content of the sUage but from other '

modifications such as 1) organic acid production; 2) degradation of

nitrogenous compounds; 3) increase of the proportion of cell wall due

to a fermentation of the cell content; 4)structural modification

during harvest1ng, storing and fermentation. ----________ 1

Harris et~. (1966) recal1ed that the low ~ntake associated

with h1gh moisture silage is generally not due to moisture per ~

" as DM intake is not,reduced when the moisture content'of dry silage

ia increased by wett1ng. Also, the DM 1ntake of silage often shows

no relationship with digestibility, so that intake of silage of (

h1gh digestibility may be Iow~

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However, this situation may not be detrimental. For example ,

in the study of Stone et al. (1960) consistent and highly significant 1

differences in efficiendy were found in favour of grass si1age as

compared with hay as a source of forage. Expressing the difference

between hay crop si1age and hay in terms of efficiency, lit was found

that 100 lb. of 4% FCM could be produced with 5 lb. less TDN when

silage was the forage source. 1 1

Thomas et al. (1969) found similar resu1ts wher,e the dry matter

of silage contained 1.24 times the digestible energy content of

companion hays.

Studying, input-output re1ationships, Murdock and Hodgeson

21

(1969) reached the"same results: milk production was maintained as weIl

or at slightly higher levels and body weights were maintained equally 6 1

weIl or slightly higher by cows on silage and hay rations as by those

on all-hay roughage. AIso, this was accomplished with a lower total

dry matter intake by the cows on the mixed forage.

In the report of Gordon ~ al. (1961), where bath direct-eut

silage and haylage were compared with barn dri'ed hay, haylage (39-53% DM)

improved DM intake over the direct-eut silage (24-27%IDM), but did'not

improve milk production. In a later report' by Gordon ~ al. (1963),

silage wilted to 38-~5% DM was equal to heat-dried bay harvested from

the same field in bath DM intake and milk production.

Whereas DM intake is generally lower for silage-fed cows

(Hemken and Vandersall, 1967), the majority of reports have shown that

milk production is as high and sometimes higher on the silage pro gram ,

as on a hay feeding program.

C)

22

Jackson and Forbes (1970) evaluating the voluntary'intake of

four silages made from the same sward with a DM content ranging from

19.0% to 43.2% concluded that a1though the si1ages made from wi1ted

herbage were 10wer in digestibi1ity than that made from unwi1ted

herbage, wi1ting increased DM intake and metabolizab1e energy intake. \

1

The effect of dry matter content of the siIages on voluntary DM intake

was described by a curvi1inear equa tion. Maximum intake "'was calcula ted

to occur at a DM content of 35.5%.

ii. T~xture and intake

Ample evidence has been published (Cunha, 1973) showing the ,

advantage of processing the hay to improve its intake.

Journet (1969) gave these intake figures (lb/day) for hay ,

fed to 1actating Holstein cows: long, 34.0; chopped 38.3; ground

47.7 and ground and pelleted 48.2. In general, the greater the reduction

in partic1e size, the greater nutritiona! advantage is gained (Ponefer,

1973).

Fewer experiments have dea1t with the texture of silage in 1

relation to its intake. DU,lphy a\i Demarquilly (1972, 1973) comp~red

the rermentation,characteristics, digestibilityand voluntary intake "

of 34 "f3ilages produced with the satne original herbage, but harvested

with either a flail harvester (10 to 25 cm 1ength material) or a

ha~vester with knives on a plate (5 to 15 cm length material) or a

precision-chop forage harvester (0.5 to 1.5, cm length material). The

results showed a marked advantage for the fine chopped silages for the \

quality of conservation and for ~he intake as observed with sheep. 1

, ... ,'f.' l ,.

1 1

) 1 '., \ ~ i

:)

( )

_._. --._. __ . --------,,------------------- -

23

There was an improvement in intake of II.9% and 43.9% of the fine chopped 1

silages over the average length and the coarse hay silages. Further

chopping after fermentation of the average length and coarse silage

improved the intake by Il.2% and 33.1%.

The authors concluded that the type of forage harvester plays

a very importa~ ~ole in successfu~ production of hay silages

,especial1y for silages with f high intake level. However even when

uti1izing a precision-chop h~rvester and an additive, it is still not

possible to make hay silages, \ Wh~ch have an intake as good as tha t 1

of hay.

Iii. pH, organic acids and bases and the intake of hal crop sliage t,

lt is generally agreed th~t high-quality silage is characterized

by a low ~ low contents of butyrie aeid, acetic aeid, and ammoniacal

nitrogen and by high levels of lactic acid (Gordon et al., 1961). 1

)

Jackson and Forbes (1970) reported that no generalization

about the relationship of pH to intake can be made. In their experiment 1

a decreased fermentation, due to the exclusion of air by means of a

plastic film, eafIsed a high pH to be, associated with higher dry matter

material.'

In the exper;Lment of Gordon et al ~ (1961') increases in dry

matter content were signifieantly correlated with improvement in

chemical quality as indicated by deereases in ammonia, acetie acid,

prôpionic aeid, butyric acid, and total acids.

Lactic acid eon~ent and pH are sometimes,used as the primary

indica,tors of chemical quality. In Gordon et ,!l. (1961) these values 1

were relatively constant, although other criteria i~dieated a wide

(

i \

difference in qua1ities. Apparently the fermentation of hay1age i8

rather 1imit d and is more conspicuous~y characterized by the absence

of undesilabfe factors rather than py the presence of desirable

fermentati0f/ end products.

" ACc~ding tOjZimmer (1971), reduction!of microbial activity,

which re~ults in lower lJvels of volatile fatty acids and deamination

has been found by many workers as the fundamental pattern of

fermentation in low moisiure material.

Wilkins ,et al. (1971) working with low dry matter silages

(m.ean 25.'0-30.1% and range 11.0-54.2%) found that voluntary intake

was positively correlated with the contents of dry matter, nitrogen,

lactic acid as a percentage of total acids. Vo1untary intake was

negatively correlated with the contents of acetic acid and ammonia as

a percentage of total nitrogep. A1though pH alone did not account for

a significant part of the variation "in intake, multiple regressions in 1 1

wh1,ch pH and one of the measurements of fermentation quality were 1

included were significant, with pH positively re!ated to intake. , /

Iv. Digestibility and chemical composition 1

, McCullough (1959) stated that forage intake is influenced by

forage qual1ty and is reflected by a positive correlation (.512)

24

betweep dry matter digestibility and dry mattèr intake. However, Stone

et al. (1960) sho~ed an increase of daily digestible dry matter intake

of 82% related to an increase of 39% in t~e digestibility of a hay, ,

cut at various stages of m~turity. 'Furthe~, Wilkins et al. (1971)

concluded that when silages from different species were considered

together, the corre1àtion between voluntary intake and the apparent

1 1

e r

un .. ",;rm; .(W*@:uit::a::"'11U4likIDi aZlIdl"I,eIJJIU JI liHUfl1ll!1U! lUi 1'141

, 1

digestibility of dry matter was not significant. However, for legumes

this correlation was significant and positive and for grasses other than

ryegrass the correlation was significant and negative. Van Soest

(1965a) found that a classification of the effects of forage composition

upon nutritive value may be made according to how chemical constitution

affects intake, digestibility, and the relationship be~een t~em.

Three classes can be distinguished (Van S~est, 1965a): 1) the

factor affects intake; but has no direct or reliable effect on

digestibility; for example, the presence of higQ leve1s of VFA in high

moisture silage; 2) a positive relationship between intake and

digestibility is promoted, for example, when voluntary intake (VI) is

inversely related ta the fiber conten~ of the forage; 3) a negative , ,

relationship between intake and di~estibility is promoted like when very

hlgh quality feeds are used in which the fiber fraction ia small and

does not affect intake.

Van Soest (1965a) concluded that chemical composition on the

whole la much more close1y related ta digestibility than VI. In some

forage species (orchardgrass, bromegrass, Sudangrass) the~relationship

between VI and chemica1 components is very high. In other species

(alfalfa, bluegrass, and perhaps timoth~) relationships are confounded,

and there is not a significant relationship between VI and digestibi1ity

or between chemical composition and VI.

In terms of chemical c~mpositiom, the only consistent effect 1 •

that can be observed for all l forages ls that l'of the ~otal fibrous

fraction, cell-wall constituents. As this fraction increases, voluntary

in~ake declines wlth increasingly negative slope. In forages with a low

25

'l' • 1 , , , -l '

1.

.'

o 1

ï 1

, 1

26

~11-waIl content, digestibi1ity and intake apparent1y are not re1ated.

In forages with a high cell-wall content intake is higll1y cor're1ated

with both chemical composition and digestible dry matter.

The re1ationship between dry matter digestibility and dry matter

intake reflecta the greater rate of passage and the resulting increase

in intake of high qua lit y forÎge. This factor is probably one of the 1

items measured when intake ia correlated with crude protein or crude

fiber (McCu110ugh, 1959). However dry matter digestibility, crude é

protein, crude fdber, and caiculated TON required yie1ded significant

influences on dry matter intake (McCuIIough, 1962).

v. Pro"tein content and intake

A low protein content in a forage i8 recognized as having a

depressing effect on forage intake. In fact roughages containing less

than 1,.0-1.2% of nitrogen decrease the activity ~e rumen's

microorganism~ (Jarrige et al., 1974).

The benefit of the addition of nitrogen to these roughages has

been shawn by Campling et aL (1962) and Donefer ~ al. (1969).

On the other side a high protein content can also have depressing \

effects on intake when this forage ls enslled. According to McCullough

(1961) the optimum temperature of 80 - I10oF. for lactic acid producing

bacteria is also optfmum for the baçteria whic~ produce volatile acids

and break down protein into simple nitrogenous compounds. However,

disintegrated protein in alf~lfa forage has a buffer capacity at pHS 1 •

which require~ 10 times as much acid to reach a pH of 4 as the , .

unfermented and intact forage proteine In a study rëIating silage

fermentation with dry matter intake by dairy cows, the factor most highly '\

"

() ,

, 1 i' 1

\

associatèd with final pH was the crude protein content of the forage.

Therefore protein and. not fiber, fat o~ ash influenced fermentation

and th1s 1s in agreement with the conjecture which conc1udes that the

factor of si1age fermentation which influences si1age intake ma~be of nitrogenous origin (McCul1ough, 1961).

vi. Intake of hay crop silage when fed a10ne or w1th hay

There are numerous reports comparing,a11 legume-grass si1age

feeding programs with hay programs or combinations of hay and grass

sllage. Some of them have· indicated (Conrad ~ al., 1958; Hil1man

et al., 1958; Gordon ~ al., 1961) that an a11 si1age forage program"

was inferior to feeding regimes of high quality hay or a combination

of hay plus silage.

Others believe in the feasibility of an aIl sllage pro gram

(McCu11ough, 1961; Hemken and Vandersall, 1967; Larsen, 1975). A

long-term experiment comparing.hay1age with wi1ted sllage plus hay

~howed a higher total dry matter consump~ion ~nd a higher ml1k and

FCM production for the haylage fed group of cows (Larsen et .!.!.., 1971).

A second experiment comparing a hay1age based ration with a hay1age

plus barn dried hay gave comparable results: Intakes were stmi1ar but l ,

the hay1age fed group produced 1.86 kg of'FeM more per day (Larsen,

1975).

McCu110ugh (1961) util1zing regression analysis to study

factors' affecting grass silage intake wh~n hay waEl fed or- not conc1uded )

;h~t the abilit;y of hay feeding to suppress (i-b regre~si.on analysis)

.. the factors which influenced dry matte~ intake of hay silage aione

may explain the frequently beneficial effects of hay feeding with

silage ,ra't:ions.

27

1 , . j ~

,j

1

t r,

.: \

b. Concentrate characteristics

1. Texture

lt is not J:he objective of this review to go over this wide

tapie on which ample references are available, such as the work of

Cunha (1973).

"

However, to stress the imporçance of this factor, some data

from lHnes (1976) are presented. l~mod~rn milking parlors cows 1>

have a limi ted access to the grain mixç~re. lt is therefore importan t

to facilitate the intake of the concentrates if they are to be fed in

milkibg parlors.

lt is reported that slurries containing up to 4 kg concentrate

in 10 1iters of water were rapidly consumed by drinking. The times

taken to consume 1 ~g of concentrate when given as a Ioose meal, cubes

and as a slurry containing 4 kg per 10 liters of water were 3.1, 2.2

and 0.6 min., respectively. Other results gave the following rate of

intake of concentrates in various forms: Ioose mixture, 291g/min;

8 mm diameter cubes, 446g/min; 1: 2.5 s1urry, 718g/min; 1: 3 slurry"

578 g/min.

il. Simple or complex mixture f

In the Quebec context of self-sufficiency and to increase

prof,itability, tlle feeding of grain grown on the fatm i8 becolJling

more popular. High moisture corn is one' of the available options"

28

either in the form ~f hi~h moisture she1led corn (HMSC) or high molsture \,

ear corn (HMEC).' -',

l " r~

" l , ,

\

) In genera1, experimental results show that either form of HM

corn is essentia11y equal in feeding value to either forro of dry corn

when fed on an equal dry matter basis. In comparisons of HM corn as

the major ingredient in simple concentrate mixtures (75-80% of the

total ingredients on an as-fed basis), milk production response has

been equa1 to or slight1y J\rea ter than that from mu1ti-ingredient \ ~

mixtures (Merri11, 1971).

ComPrring four rates of concentrates given on a FCM basis,

Lamb ~ al. (1974) have fed a simple mix based on barley and beet pulp .. "

and a 10mplex 14% protein mix ta lactating cows 01\ a high-quality

alfalfa hay. Differences between grain mixes were not significant for

any traits except percent milk fat and total solids which were higher

ln the

iiL

simple mix.

Level or amount of concentrate li

The extent ta which the increased consumption of concentrate

29

affects the ~oughage intake has received a general agreement throughout

the literature.

The experiments of Jensen ai al. (1942), Murdock and Hodgson

(1969), Lamb et al. (1974) show a decrease of 0.4-0.7 kg of roughage

intake for every additional kg of concentrate consumed. Values of

Journet (1969) and Jarrige et- al. (1974) are a1so in~reement. Journet

(1969) suggests a rate of decline of 0.30-0.~,kg of forage per , -

a~itiona1 kg of gr~in for a low quality hay, 0.5 kg for the 'average

hay and 0.60-0.7 kg for the high qua1ity one.

'Usua11y the decreases in roughage consumption are low ~Qr silage

~' I:J

o

30

rations when grain Is fed. For example, a decline of 0.30-0.5 kg of

grain was found by Jarrige et al. (1974), 0.24 by Mather ~ al. (1960)

for a ration based on high moisture silage. They also found that the

effect of grain feeding on roughage intake decreased with an increase

in the genetie potential of the animal. On the average, for each

1.000 lb. increase in production, the effect of grain feeding on forage

intake decreased 0.17 lb.

In his review, Bines (1976) recalled that the addition of up to

8 kg peI' day of concentrates to rations of, cows offered silage

ad libitum had 1itt1e effect on intake of silage.

Kesler and Spahr (1964) indicated that maximum nutrient intake

occurred in high-producing cows when concentrates composed from 50 ta

607. of the ration. 'Journet (1969) suggested a proportion of 50 to

707..

c. Complete rations characteristics

Some important criteria used to compare the feeding value of

different ations are based on characteristics of the total ration or

complete ration. Since the use of these rations ls becomlng more common,

their analyses require a special approach.

i. Digestibi1ity

The relationship between intake and digestibility is a

curvilinear one resulting in maximum intake in most rations between

65 and 68% digestibility. Thus both high and low percentages of

digestibi11ty exert adverse influences on feed intàke (McCullough, 1973):

Accord1ng to Conrad et al. (1964) physica1 and physio1ogical

factors regulating feed intake change in importance ~th increasing J

digestihility. At l~w digestibility (52-66%) they ~ere: body weight <>

JI au

"

J. hUE fF.III'4 S

"'" , (

(ref1eeting roughage capacity) , und1gested residue per unit body

weight per day (reflecting rate of passage), and dry matter

digestibi1ity. At higher1digestibilities (67-80%) intake appeared

to be dependent on metabolie size, production, and digestlbility.

Curran et al. (1970) observed the relationship of increasirg

voluntary intake, with increasing digestibility of the diet. However,

in opposition to the finding of Conrad et al. (1964) they have not

found a clear demarcation between the inereasing and decreasing phases

~ of intake in relation to digestibility as previously set at 66.77..

ii. Calorie density

The concept of the effects of calorie density on energy intake

by dairy eows was earlier introduced (II.A.3.b.).

Bull ~ al. (1976) proposed a re1ationship between digestible

energy intake (kcal/day per kg MW) (Y) and calorie density (Meal/liter

dry matter, as fed form) (X) where Y = 759.2 X - 148.4. They reported

a simple correlation of .99 for diets with calorie densities of

.58, .63, and .68 .. It ia beneficial to recal1 that in their trial, the 1

diet with calorie density of .68.repreaented the point above which 1

physiologiea! regulation was employed by/the animals.

According to McCullough (1973), the d1nsity of rationa apparently

a1ao exer~a a curvilinear influence on feed, lntake. In most dairy

rations, the major influences of density can be overcome bY,includi~g

35 to 55% grain in the total ration.

t'

Q 1 ~.;t.t •. ,,"a •.... -: .. , ~~:j;~'{~1<s;;l;:':~~' ~~;a. ,~t;;;I ... _IINFI!il·IE.NI!;lImrll!!!!I~gi\!!llLIIIJI! .• IIlIlM��!!!!L ...... --------------

, .

31

J,

t ·Hi. Ration balance

Feed intake is influenced by ration balance primarily in

relation to the influence of the ration on rumen fermentation. Thus

ration balance for crude fiber, starch level and other factors which

may slow up'passage of the feed or improve rumen fermentation is

important, in feed intake. A frequently quoted example ia that of

protein. Rations for sorne animaIs functions such as maintenance , can be calculated in which the protein requirement for body functions

1 • is lower than the protein requirement for good tumen fermentation.

t:.~} , For this reason, no matter how low the calculated protein requirement

may be, it is not recommended that less than lOi. protein be included

in the ration to insure good rumen fermentation and feed intake

(McCullough, 1973).

IVe Blended feeding

High producing dairy cows have difficulty consuming sufficient

quantities of grain in the milking parI or within the normally allotted

milking time. One alternative is to eliminate aIl feeding of grain

in the milking parlor, rather blend the proper proportions of forage

and copcentrate in a complete feed and self-feed the various mixtures

based on group production levels (Coppock et al., 1974b).

32

Feeding ~ystems which do not'permit individua~ choices are"

valuable in nutrition r1esearch trials in which one attempts to minimll.ze

e~raneous sources of variation and ta specif~cal1y describe the exact

diet eaten by aIl animaIs. Effective least cost ration programmin'g

requires not on1y an accurate knowledge of the composition of the

" !

t ' feedstuffs, but it also is necessary to be able to control their

proportions in the dietl to balance the ration and achieve the level~

of performance that w~ll give least cost performance (Coppock

.~ al.. i974a). /)

Stallcup (1975) in reviewing the topic showed that when the

roughage to concentrate ratio averaged out near /

concentrate and silage separately in the conventional ma~ consumed

total dry matter at 2.8% of'BW vs 3.3% for cows fed a complete ration.

In another study, Sta11cup (1975) showed resu1ts comparing COW8

individua11y or group fed: the group fed cows consumed 7% more dry

matter.

4. Environmental characteristics

It i8 not the objective to review aIl or even a part of the

available evid,nce on this topic. ~owever, it is mentioned to stress

how extreme conditions of environment c~ affect food intake.

a. Climatic effects

It is weIl known that rising air temperatutes are accompanied 1

by a decline in total feed consumption. Brody (1956) showed that the

TON consumption at 35 and 37.8C was one-ha If and one-third of the

level consumed at 21.lC. ';Johnson ~ al. (1966) saw a decrease of

10% in total DM intake when temperature rose at 8.3 degrees above

seasonal normal. ~ 1 Exposure.to extreme cold likewise influences forage intake.

McDonald an4 Bell (1958) showéd an,average difference of 2.4 kg in

daily hay intak~ when cows were subjected ta moderate (daily minimum

33

of 4.4C) or very cold. (daily minimum of l7.8C) "temperatures. The colder .1' 1 1

t

1 ",

, '

/'

{

the weather, the greater was the appetite for forage.

Relative humidity, wind velocity, and solar radiation have \

contributory effects on appetite regulation, mainly in situations

of hest stress. In general, any action of\these climatic factors

that adds to an animal'~ heat load will cause a lowering of the 1

critical temperature at which feed consumption begins to decline, and

any action that tends to Bubstract from the heat load will cause this \

critical temperature to rise (Brody, 1956).

Casual observations of grazing cattl~ suggest that eating is

reduced during periods of heavy rainfall (Bines, 1976).

34

Webster (1976) recently publish~d a rev~ew on the influence of the

climatic environment on the metabolism in cattle.

b. Shortage of water

Water restrictions inhibits intake of food by mammals including

l ruminants (Utley et al., 1970).

In general there is a direct relationship between the amounts of

food and water voluntarily consumed (Binès and DavfY, 1970).

5. Predictive eguations

An outstanding number of equations have been worked out with the ,

objective of explaining the variations encountered in dry matter ~ntake

(DMI). Few have really been tackled to determine factors which would

be of practical application to predict DMI irr the several different

situations usually found on farms.

This section presents some pf these equations, a f~ deal with

ration characteristics only, others deal with cow characteristics and \

most of them with both. They will be presented accordingly in that

sequé'nce.

iL

! ( ) \ ! 1 , 1

.'1 1

1

j -, 'J •• "Jo

' .....

a. Equations predicting DMI based on ration only

Many studies (C.3.a.i.) have related the DMI of si1age to its

DM content. Jack~on ~hd Forbes (1970) have fed legume-grasB silag~s

differing in D' content to crossbred Hereford cattle. The effect of

dry matter content of the silages on voluntary DMI was described by

the curv~linear equatiin:

y = 5.477 X - 0.077 X2 (Residual SD, 10.034)

W'here:

y J dai1y DMl (g/kg wO. 73 ) and X = percentage DM content

of the si1age corrected for volatiles.

Larsen (1975) who fed haylage and silage plus hay to lactating 1

cows derived an equation, which predicts DM consumption based on the

35

percentage of dry matter content of the forage. The prediction equation

is curvilinear between 38 and 72% DM and is as follows:

y = Il.5 + 0.816 X - .0064 x2 1

Where:

y = predicted DM consumption in kg/cow/day and X is the

% DM of the haylage being fed. No measure of accuracy

ia, given.

Stallcup (1975) fed Holstein cowa with alfalfa-grass hay at the

rate of 1 lb/lOO lbs. bod~ weight per day plus corn and sorghum

sllage free choice plus a supplemental concentrate. He found a ,il ['

\significant negative correlation between total DM l and diet crude <

fiber percent (range of 14.5 - 25.0% and average of 18.6%). This -':;". 1 ,

relation ia expressed by the pre<Hctive equation: -

!

q

"',.

1 i

'A

36

y = 3.696 + 0.1579 X - 0.0093X2 (l? == 0.37)

Where:

y = DMI in Ib/IOO lb BW and X = crude fiber-content

of the diet.

b. Equations predicting DMI based on cow status on1y ,

The fo11owing studies expressed the var~ation in DMI by the

dif-ferent characteristics of the 1actating cow.

Stone et al. (1960) studying data from 12 forage experiments

invo1ving 175 Holstein cows fed hay or hay silage produced a

multiple r,egression to adjust for some measurable variables as follows:

y = 5.92 + O.097A + O.012B + 0.0946C (R2 = .25)

Where:

y = lb. of forage DM! dai1y; A = lb of FCM produced

daily; B = lb of BW; C = lb of daily'weight change., "

Journet (1969) pres~nted a similar equation from a studi\pased

on 242 Friesian and Normandy cows fed grass silage, hay and suga} beet:

y = 7.54 + 0.811

0A + 0.027B (R2 = .50)

Where:

y = DM! in kg/day; A = BW (hundreds of kg) and B,=kg ,

of FCM/day. \

Bines (1976) gave a comparable simple-predictive equation to

evaluate the probable dry matter appetite 11mlt:

y = 0.025 A + O.lB

Where:

y = DM! in kg/day; A = BW in kg; B i8 ml1k yield in kg/day.

Thus, for a cow of a given weight, the intak~ of dry matter will increase (,

'by 0.1 kg per 1 kg increase in milk yield.

(

;

" ~ 9 i l'

, \ -'

':'"if'~"tl:~J!':I~I'l!I!If""'_'1><M""'''''''''''''''''~ __ '''''''""",,M ...................... "" .... ec ... , ... "' ...... ,.....",,'"'J"" ..... ""' ........... ,,""'I!I!ISi.,U_II:n.AW_tlllllllilllll41I111'I~J. •• IiII.IIII!I •• U4!1_11!!11'p_."'èt __ lIIIIs.a., •• IIIIJ •• LII •• I5"UIJI!J1161001lll, •• I", •• 1

McCullough (1961) working with silage ration studied several

factors associated with fermentation in a step-wise analysis. He \

proposed several equations, the following is one:

y = 1.933 + O.Q2Q5A Q.Q51IB (R2 = 0.43)

Where:

y = .silage DMI/dayj A = BW and B = milk production/day.

Up to now none of the proposed models has explained more than

50% of the variation encountered in the evaluation of DMI. lt is

therefore easy to ~tate that neither the cow's characteristics alone,

nor the forage's characteristics alone can be adequately used to

predict DMI.

37

c. Equations predicti'ng DM! based on rations and cow characteristics \

Monteiro. (1972) has deve10ped a comp1ex model which takes account

of weight changes, time during lactation and delays in response to food

intake to previous changes in both milk yield~ and gain. Food intake

is expressed in terms of weight and takes into account some effects

of ration composition by including conversion factors of food into

milk and weight gain. 1

This model is different from the previous ones in two aspects. 1 1

First, it combines components of the cow a~d the ration. Seco~d, it

incorpora tes a time factor for the delay in response. This Is the

strength of this highly sophisticated mathematical model. Although

the number of cows in his experiment ls low (eleven cows), the model

1

explalned 92-98% of the variation in DM! when the delay factor was

" taken into con~lderatlon. Wlthout this factor only 45-90% of the 1

variation was explained.

'.

'\

The complexity of the model inhibits its presentation in this 1

r'eview. Nevertheless, the model is nonetheless important and looks

very promising for future utilization.

Other models more conventional but often quite accurate are

also available. For eJample Richards and Wolton (1975) worked with ~

dairy and beef animaIs fed grass silage preserved with or without

formic acid. Silages were fed ad libitum and a concentrate was fed to

complete the ration.

38

Multiple regression analysis was performed and the developed model

was used to predict silage intake of large groups of cattle with good

accuracy. The equation is:

y = 0.133A - 0.282B - 0.364C + 0.155D - 3.54 1

Where:

{R2 = 0.963)

.. . y = silage DM! (kg/head/day); A = silage DM content

(% of fresh weight); B = silage pH; C = intake of other

DM (kg/head/day) and D = MW (kg).

Other British workers, Curran et al. (1970) reviewing five -- 1

l

different trials involving mainly hay feeding and a few si1age feeding.

trials proposed the following model tg' evaluate the voluntary intake 1

of dairy cows on winter diets in the first 16 weeks of lactation:

,\

, y = -16.921 + 0.332A + O.730B + 0.644C

1 Where:

y = total organic matter intake

A = live-w~ight change (lb/day)

0.333D + O.005D2

2 (R = 92.8)

B = weight of concentra tes offered (lb of organic matter/day)

C = royghage dige~tibil1ty

D = milk yield (lb/dayy

"

di Il&! bU. dl Il SU Ltl •••

39

The observed"intakes of cows not included in the study were compared, with

those predicted by the mode1. It demonstrated the feastbi1ity of

predicting voluntary' intake in any group of cows given the relatively

easi1y recorded values of mi1k yie1d, quantity of concentra tes offered

and digestibility of the roughage. 1

Although less interesting from a prediction point of view, the

data presented by Johnson et al. (1966) are interesting because they \

stress the most sigriificant factors affecting DM!. These results evaluate

the relationship between different factors over a complete lactation.

y = 3,4B5 + O.366A + 1.B5B + 1.99C - 1.760 (R2 = 0.53)

Where:

y = predicted 30B-day total DMI from hay and silage (kg); 1

A = 30B-day FCM (kg); B = BW (kg); C = net gain in weight

(kg); 0 = 308-day grain DM!. (kg). _

\

It ia interesting to note the constancy in the variables invo1ved

in the last two models: mi1k production, weight chànge, amount of , \ ' -

concentra te. These factors are again mentioned in the next model df

McCullough (1973):

y = 5.380 + 0.008A + 0.359B + 4.7l9C - 0.0280

Where:

y = dry matter intake (lb); A = BW (lb); B = daiIy milk

production- (lb); C = gain in weight (lb) \ ~nd ]j = percent

grain lin ration. 1

The equation derived from 39 feeding trials conducted at severaI

\ ' different expertment stations throughout the United States is expected

\ ,J

ta predict the intake of the ration within 7 percent of the actual intake. "\

,1

\ ,

I\J\Wi4IUI!!O;g ,utAtQWiOU !lits.. ua! .1 n r

Other modela have bee~ previous1y presented by McCu110ugh.

Those ~ere more orientated toward the identification of the factors

inf1u)ncing the DM! of silage based, diets.

McCu110ugh (1961) presented this equation: \

y = 15.84 + O.014A + 0.022B + 0.2610 - 1.390D + O.053E -

0.395F (R2 = 0.69)

Where:

y = silage DM! (lb/day); A = BW (lb); B = milk production

C = sil?ge DM; D = silage pH; E = silage crude protein;

F = si1age crude fiber.

40

In 1962, McCullough produced this stmilar equation~for predicting

silage dry matter intake:

y = 17.60 + D.209A - O.477B - O.239c + 0.346D 2

(R = 0.928)

• Where:

y = silage DMI; A =, dry matter digestibi1itYj B = crude

protein; C = crude fiber and D = calculated TON required.

The negative value for protein.is remarkab1e.

The next two mode1s were derived by Conrad et al. (1964):' the -

first one le for ration of low digestiblli~y content «67%) whereas the

second ls for ration with a higher digestibility as reported by

MeCu,llough (1973).

Equation 1: (low digestibility ration)

log Y =,1.53 log A + 1.01 log B * 0.99 log C - 5.296

Where:

y = DM, (lb/day); A = digesti~ility; B = fecal

DM/l,OOO' lb; C = BW,'

2 (R = 0.995)

o

1\

Equation II:- (high digestibility ration)

y = 10.7 (A/IOOO) + 0.058B + 0.33C + 0.53

Where:

y = maximum feed intake (lb/day); A = BW; B = MW

(BW· 73 ) and C = milk (lb!day).

According to McCul10ugh (1973) who had used this formula for four

years to calculate rations used on hundreds of farms, the ca1culated

feed~akes appear to be within 5% of the measured intake in most

herds.

d. Linked ta least cost formulation

The next two models were expressly developed to be integrated

41

with 1east cost formulation of the entire ration. One was put forward.

by the Virginia Polytechnic Institute and the other by the University 1

of Ca1ifornia, this !ast ~>ne formulating a "maximum profit ration".

Chandler and Walker (1972) generated an equation for predicting ,

DM! of dairy cattle from statistical analysis of 207 cow balance trials

collected over 5 ye~rs: , '

y =[3.625 + 0.076A - 0.170B - 0.026C + 0.01017 (0 xE)] B

Where:

y ='DMI, kg!cow!day; A = type of feeding, winter feedfbg /

(corn silage) = +1 and summer feeding (barley silage)

= -1; B = BW, kg 100 weight; C = crude f[ber, % of dry . , matter; 0 = daily milk production, kg; land E = fat test, %.

The five independent factors aIl significantly affected OMl and

when included together in the multiple regression model, predicted DM1

with a R2 of .80.' ~ 1

42

. In this model a complete set of mathematical equations has been

included in a computer program for generation of nutrient specifications 1

for least cost ration formulation. r-

This program gives the nutritionist the ability to determine

immediately changes in nutrient specifications as a result of variable

productive-conditions and to apply linear prQgramming to aIl situations.

The next and 1ast pro gram presented in this review is weIl .

documented in a booklet written by Dean"êl: al. (1972). Part of the data

:Lnvo1ved in this progralÎl are also avaïl~e-:-n a book written by Heady

and Dillon (1972).

This computer linear program formula tes dairy cow rations that

maximize ipcome ahove feed costs. It incorpora tes aIl of the features

of a least-cost ration program plus many other features that must he

considered to ohtain maximum income above feed costs. The program

considers feed costs, nutrient requirements, the price received for milk,

ma;l.~fenanèe r'equiren1ents for cows of various body weights, pro duc tion

requirements at various level~of milk production and fat tests,

maximum voluntary roughage intake as cœcJntrate intake is incre~sed,

and minimÙm fiber and roughage levels to maintain normal milk fat "'-,

tests. With this information and data on the nutrient content of the

available feeds, the computer tests every feed combination that

fùlfills the major nutrient requirementk sr dairy cow, or group of , \

cows" and selects the combination that results in maximum income above

feed 'costa

In this program it is felt that maximum voluntary intake

estimates are affected by the bbdy weight ànèt productive capacity of

..

•

\ 1

43

.' the, animaIs. Therefore, twa underlying assumptions are made on rough~e

intake. First, the maximum quantity of an excellent quality all-roughage

diet (pounds of hay plus silage expressed in terms of 90 percent DM

content) that a dairy cow can voluntarily consume ls taken as 3.5 percent ,

of BW. Secouai;, a minimum level of roughage that should be consumed'

by a dairy cov to prevent depression in milk fat is taken to be 1.5

percent of body weight.

The curviU.near maximum voluntary intake li'ne for medium and

high producers i8 approximated by two Iinear segments:

y ~ 49.0 - 0.33A

y ~ 53.5 - O.68A

~ Where: l~

y = maximum voluntary intake of roughage and

A = amount, of concentrate fed.

Mo.~e' {~.

than two linear segments cannat be used in this case, because

of problms of linear dependence. However, since the maximum voluntary "

intake is n~rly lin~a~ over the relevant range, approximation by only

two linea~ segments is quite accurate. This statement 1a confirmed by 1

thé review of SmIth (1976).

",r Therefare the maximum voluntary intake of excellent quality

~falfa hay la set at 3.5 ~ercent BWand the maximum voluntary intake of

90 percent dry mattèr equivalent of: silage Is set at 2.5 percent BW.

These last t~o mode~s are of resl Interest because they show how

important the evaluation of the vo1untary DMI is when we want to improve

",' our knawledge of a' better choice of feedstuffs for the optimum combination.

-.

44

III. OBJECT OF RESEARCH

The study was conducted to eva1uate the response of cows of

high genetic potentia1 fed a high quality hay crop si1age at three ~

different leve1s of grain per kilogram of milk. These evaluations

invo1ved:

1. Week1y determination of the hay1age and grain

intakes as weIl as the weight of the cows and

mi1k produced.

2. Weekly determination of the chemica1 composition

of the milk.

3. Weekly determination of the' chemical composition of

the hay crop si1age and the grain mixtures.

4. Collection of data related to the health and

reproductive status.

5. Evaluation of the factors affecting hay croif silage

intake and their predictive value.

6. Comparison of the voluntary intake of nutrients

versus their theoretica1 requirements.

7. Estimation of production functions to evaluate the

\ economic contribution of the different feeds.

o

( j,

\ J ,

45

IV. EXPERIMENTAL

A. GENERAL PROCEDURES

1. Introduction

This trial was conducted at Macdonald College farm from June,

1975 to July, 1976. Only Holstein heifers and c1Cj>ws were used.

2. Experimental Design 1

The experimental design consisted of an 18 w,;eks continuous lactation

trial with three treatments imposed. The three treatments comprised three

1evels of grain feeding. The grain feeding levels were based on the

weight of grain allowed per -kilogram of mill<. The three grain feeding

rates are as follows: /

~ed \ \

\ 3.

1) high (H) l kg of grain per 2 kg of fat corrected mUk (FCM)

2) medium (M) 1 kg of grain per 3 kg of FCM

3) low (L) 1 kg of grain per 4 kg of FCM

AlI cows were allowed alfalfa hay crop sUage free choice. COWB were

in stanchion barn equipped with individual feed boxes.

Cows

E~ery cow ca1ving during this period wa~ put on tbe trial after

calving. The pre-calving ration consisted mainly of hay crop silage plus

hay and grain at the 1. 5% B'W 1eveI. Before the experiment started, the

anima1é were random1y assigned ta one of the three groups. Cows which

had at least one record wer~ ~anked according ta p~oduction with,the

dairy herd ana1ysis service (DHAS) cow rating. For beifers an estimate

•

L

() o '

46

~ - t of production abilit~-~alculated from information available for

their dam and sire. Young sires were assumed to be at least average

for the national herd while figures for proven sire~ were based on

their production deviation based on herdmate comparisQn. The contribution

of the dam of a heifer was estimated as follows (Moxley, 1975): \

" " (Number of records x 0.25 ) x (1 + (number of records -1) x 0.4)

Average deviation of the dam from the herd

The heifer rating was tben calculated as follows: ,

ratling =DAM'S deviation + SIRE'S deviation'-\ 2

After the animaIs were ranked, th~1 were randomly

three treatments. Initial1y each treat~nt consisted of

assigned to the

equal numbers of r cows 'and heifers. However some reassignment was necessary due to health

problems at calving. The final groups are presented in Table 1.

, Table 1. Cow and Heifer Rating and their Distribution

Betweèn theJThree Groups.

Cows

Heifers

Nb

Aver.!

St. Dev.

Nb' 2

Aver.

St. Dev.

Total' Anitnals

Hish

9.0

106.1

lL2

6.0

2.3

6.0

15

GROUPS

Medium Low

8 .• 0 12.0

101.7 ~3~ ~~ 1'0.7

7.0

2.0

5.0

15

3.0

1.5

4.2

15

------------

r ________________________________________ ~--------------_T

1 DHAS COlt rating

2 Expected av~rag~ deviation from the mean (J.O.P.)

/

"

i

I(

, .

Note that there are fifteen animaIs per treatment or a total of 45

cows. Appendix Table l presents the complete distribution of the '--- . individual cows and~heifers.

4. 1 Hay C;rop SUage ,

47

.JI

The alfalfa (Iroquois Variety) was, harve1ted after being partially

wilted in the field. At harvesting, the alfalfa was about li/ lO in

flower; it was 90-95% pure stand, the balance being either timothy or

bromegrass. The harvester was adjusted to a theoretical length of

6 to 7 nnn.

Four different cuts were used during the trial. These different

forages were put in the same silo due to a lack of facilities with

capacity large enough to store the cuts separately. The first, second ând

third cuts were harvested during the first week of June, July and August,

respectively. The fourth cut was harvested at mid-October. No additives

were added to the hay crop when it was put in ~ top unload1ng concrete

stave silo.

Haylage was fed ad libitum, allowing at least a 10% extra over the .,

maximum daily consumption.

5. Grain Mix~ure

Two different grailn mixtures 'were used during the experiment. T,he

first one was produced on the farm with a stàtionary mix-mll12, using a,

9.5 mm. screen. The use of this grain mixture was discontlnued after the

twentleth ~eek, due to the presence of Zeralanone and Aflatoxin in the

1 high moisture corn. . ,

Synonyme for bay crop silage are HCS or Haylage

FARMACO, St'. Hyacinthe, P. Q.

1

"~' .• IUUU' 1It1 __ mcullfttE ! UtAiSlUUU Si _ikEa. 811 •• EtUI.11I II· thll 1 1 J JI 21

.. ,,1'

'From the twentieth to the fiftieth week, a commercial grain °

mixture was used. Table 2 shows the physica1 composition of the two

grain mixes. ,'"

Table 2. Physical Compositio~ of the Grain Mixes

Farm Produced

As fed percent basis

°High moisture Corn . Oats or barley

Commercial 1 supplement 2

Commercial min. mix

0.550% 0.165%

0.250% 0.035%

1 Feeds Act Registration No. 56~7

2 Feeds Act Registration No. 13387; 1

Commercial,mix 1

Bar1ey Wheat shorts Corn gluten feeds Barley malt sprouts Alfalfa meal Salt Dicalcium phosphate Limestone Dyna-tpa te3 Molasses Vitamins and salt

J ,International MineraIs & Chemical Corporation ·(Canada) Ltd.

0.150% 0.450% 0.200% 0.070% 0.025% 0.010% 0.033% 0.910% 0.005% 0.048% 154 g

, "

48 ,

Grain was fed twice ~ day into the same box. Grain not consumed was ,

weighed and removed the next morning.

6. M:f..1k Samp1ing

. Every week aIl the Macdonald Coilege 1.erd is samp1ed on two

consecutive milkings, thus data were a~ailab1e on a weekly basis for fat and \

protein cQntent as weIl as mi1k production.

/ ..

\

~ .......... ~------------------------

t

71 iUtlS.aUbl ::MU

a. Fat percentage determinatto~

Milk fat percent was determinéd bv the Milkotester Automatic /'

1 (MTA) instrument t after heating, homogenizing and diluting the sample 1

with 3 protein-dissolving Versene solution (Ethy1enediaminotetraacetic

acid) (Esan 1971). The fat content is read directly by a photometrie

measurement of the turbidity due to the fat globules •

. b. Protein percentage determination

Mi1k pr~tein percent was determined by the Pro~Mi1k Automatic (PMA)

iL nstrument This apparatus uses a method based on dye-binding. The

principle i8 based on the fact that in acid solution the proteins of milk

bind basic dyes which precipitate with the pro teins in a protein-dye

49

complex. The quantity of dye bound is pr9portional to the amount of protein

and the~amount of dye remaining in solut~on can be determined ustng a

co1orimeter (Esan 1971). The MFA uses Amido Black as d~e solution.

7. Sampling and Storage Technique

Bath the 'haylage and ~he graiIhmixture were sampled twice a week.

These two samples were p1aced in a freezer at - ~O c.

After being dried, at 50 C in forced-air oven, the samp1es were

ground in a Raymond laboratory hammer miU equipped with a l nnn screen

:(U.S. standard sieve N~. 18), and stored in transparent po1ypropylene

sample containers with tight-fitting caps.

8. Chemical Analysis

a. Dry matter

The dry matter of the original materia1 was determin~d using a

1 Foss E1ectric, Hiller,d}- Denmark.

. \ L'

, , l

"'1

'~$?~~.M')~"i4l AIl';U .c· MlllU M$.aili!l14'."tllid .•• U .la_c •• '.J •• U".U •• U •• ZlI.i \

50

forced-air dryer set at a temperature below·50oC as suggested by

Van Soest (1965b)to prevent the formation of artifact lignin via the " \

non-enzymic browning reaction. HOwever Larsen and Jones (1973)

1 demonstrated that this method underestimates the dry matter content of

wet materia1s as a result of the 10ss of volatile compounds (i.e. VFA,

lactic acid, ammonia, etc.). They proposed that the dry matter should

be determined by the toluene distillation which al10ws correction ror '->

volatiles lost into aqueous distillate. Aerts et al. (1974) concluded

'that the to1uene distillation method is not suitabl~ for routine use

because it is a long and time consuming procedure. Demarqui11y (1973) . mentioned that there is a close relationship between oven-dried and to1uene

distillation values. He therefore suggested an equation re1ating the

two values. This relationship was uti1ized to correct the dry matter data.

y' = 1,006 x + 0.986 r = 0.944 1

where: 1

Y = Adjusted toluene dry matter

X = Oven determined dry'matter

The samp1e dry matter was determined according to A.O.A.C. (1975).

b. pH determina tion ~

Fifty g~ams of fresh HeS and fifty ml of water were put in a beaker.

The beaker ,was covered and 1eft overnight in the refr!gerator at 4°C. 1 !

The ,sample was thEln 'filtered through à cheesec1oth. The fi1trate was 1 1

reeovered and pH measured with a standard pH meter.

c. Nitrogen and prote!n determinations

() i. 'Crude prote!n

The eTude proteii was determined according td A.O.A.C. (1975).

, ;;.

()

()

1 "_\"_.~ __ ._._..:\_, ... _ ............ _ ... -....... 10.,;.,; •• II1II_l1li __ ... ;; •• : ..... 1 •• : ....... 4111 •• _1. Ill. 1\IlI __ .III1.lIIlbl3l1.IISS ___ iM: ___ r lIiI .... .,

51

iL Acid detergent nitrogen

As suggested by Van Soest (1965). and deseribed by GOéring and

Van Soest (1970), acid detergent nitrogen (ADN) was determined to

estimate the amount of non-avai1ab1e protein resu1ting from the Maillard

non-enzymie browning reaetion in the feeds. This reaeti~n typieal1y takes

place in alf~fa hey erop ailages.

iii. Digestible protein (DP)

For the grain mixt~re, the,digestible protein was eseimated1by a

regression equation propoaed by Knight and Harris (1966):

y = 0.918 x - 3.98

wher-e: \

y = % digest:db.le protein

X = % erude protein [

For the hay crop silages," the method of estimating DP proposed by

Goering et"a1. (1972) based on the aeid detergent insoluble nitrogen was

folfowed.

The equation for determining nitrogen

y = - 1. 02 x + 72.96

where: /

Il digestibility ia as followa:

R2 = 0.86

Y = % Nitrogeu digestibility

x = aeid detergent insoluble protein (ADN)

Note that ADN ia expressed on a protein ,equiva1ent basis. 1

d. Fiber analysis

i. Neutral detergent fiber (NDF)

1

" ' Frir the hay1age samples, NDF determinatious were according to Goering

and Van Soest (1970).

,1

1 ! Jl

J

j

o

{ ) -! '

-, ,

~ __ .. ____ ."' _______ . ______ ..-: • ..... _0 ......... 4i ..... &IIIAIIfI' .......... .:Mt"It!IOO"'.plli!Wr\l ............ II=IIIIlII!--?"'ii!II!IKI#!I'rIIII:=IIIIW~j(l'IIIe.!JIIII_ .. J •• =_Xll!lllffllt ._,II!",III!.III!II .... ~Wllll!l'lla.,....,"tJI't

52

For the grain mixtures, the modification of the previous method

as suggested by McQueen and ~icho1son (1975) was followed.

ii. Acid detergent fiber (AnF) and acid detergent lignin (ADL)

These two analyses for both grain and hay crop silage were according

to Goering and Van Soest (1970)~

In order to correct AnF and ADL for heat damage, adjustments were

according to Van Soest (1965b):

1) Eguation for correcting ADL

Where:

y = ADL, corrected

/ XI= ADL uncor~ected

X2= ADN/B. 75

2) Equation ~or correcting AnF

y = ADF uncorrected '+- ADL corrected - ADL uncorrected

Where: 1 Y = ADF corrected

i11. Hem!cel1u1ose

This component was obtained by subtracting NDF minus ADF, as

suggested by Van Soest and Moore (1965).

iVe Cellulose

The method of Crampton and Maynard (Î938) ~odified by Donefer et al. . (1960) was used for both grain mixtures and forâges.

1 e. Nutritive Value Index (NVI)

The NVI Index, originally describèd by Crampton et al. (1960),

was determ1ned from the dry matter disappearance (DMO) vaiues according

0,

~p~.··\~~j~.\~,ti'!t~tl '. 1., ." .... L!!

1 \

o

1

. \

1211al._.; sta

to the laboratory techn1qJ'ès developed by Donefer ~ al. (1963) and th.e 1

relat10nship between NVI and DMD proposed by Donefer ~ al. (1966),

f. MineraIs determ1na tions

1 Atomic absorption spee trophotometry was used for the ana1ys'is of Ca,

Mg and K according to A.O.A.C. (1975),

The P analysis was performed by a photometrie method aacording to

A.O.A.C. (1975).

1

9. Extrapolation of the Ng1actvalues

Four different steps were involved in the extrapolation of the

NElact values.

The first atep was the estimation of the digestibi1ity. This was

accomp1ished by using the summative equation presented in the Agriculture

Handbook 379 (Goering and Van Soest, 1970). which gives the estimated

apparent digestible dry matter of the sample ana1yzed.

The second step was the conversion of digestibility into an estimate

bf TDN, which was done according ta Van Soestl(197l). "

The third step was introduced to account for the decrease in

digestibility with an increasing leve! of feeding. Tyrrel1 and Moe (1975)

suggested that the best esttmate for TON of a feed fed to a lactating cow ,

18 to reduce tabular val-u~s by 12%.1 This factoris in close a~reement .. , l

53

w1tb the discount value proposed by Van Soes't (1973) for alfa,lfa1r Therefore .. . l

'\ i \ the value obtained in the second step was devaluated to accqbnt for the leve1

of feeding.

The fourth 8~ep givee the NE1actvalue from (;

,l' l

/ " the TDN' in relationship

1

with the ceU.wall content according to Van Soest (1971). -..., \

()

o

Examp1e:

y =~8{100 - NDF) + NOF/100 (147.3 - 18.9 10g10 [(ADL/ADF)100] )

- (ADL cor.rected - ADL uncorrected)

Where: '

y = estimated digestible dry matter

2) Y=X-(36.57-0.275X)

Where:

y =estimated TON value uncorrected

X =estimated digestible dry matter

3) Y = 0.88 X

4)

Where:

y = estimated TDN value corrected

X = estimatéd TDN value uncorrected

y = .01 X (2.86 - 35.S/(100-NOF) )

Where:

y = estimated NE1act

X = estimated TON value corrected

10. Fat corrected mi1k (FCM) values

•

The basic expression wa~ app1ied accor~ing to the work of Gaines 1

and Davidsbn (1923):

FeM (kg) = 0.4 (kg of mi1k) + 15.0 (kg Qf fat)

54'

p '11. Evaluation of the requirements of the 1actating cows

Sincè the publication of the 1ast edit ion of the"Nutrient Requirements

of' Dairy Catt1e (Loosl!, 1971), new basic data have been proposed.

One of these concerns the requirement~for the maintenance of the

1actating cow • Moe, et al. (1972) summarized 543 energy balance trials and • -- 1

\ conc1uded that tHe amount of energy required for the maintenance of a

55

non-pregnant, laetating cow is .073 Meal NE mi1k per kg· 75 body weight. J

This v~ue differs from the .085 Meal NE milk pet kg· 75 body weight for

the 1971 NRC recommendations (Loos1i, 1971).

A1th0ugh this change is proposed for the maintenance requirement,

Moe and Tyrrell (1975) considering the requirements for the mi1k production

stated that because the amount of bnergy required in exeess of maintena~ per unit of mi1k produced does not change with inereasing mi1k production,

it is inappropriate to state different requirements for high-producing

cows and for low producers~ Therefore the requirement per unit of mi1k , produeed remains the same as t~ 1971 NRC figures. .

For the first and second lactation cows, inereased a110wanees in NE

requirements of 20 and 10%, respectively, were made to account for

body weight gain •.

Consequent1y these resu1ts were used in the computation of the

requirements of the 1actating dairy cows on this project.

Requireme~ts (Loosli, 1971) for digestible protein and mineraIs such

as Ca, P, Mg and K were ca1cu1ated and compared with thè actual intakes

of these nutrients.

l'

12. Statistica1 analysis

Ana1ysis of variance, correlation and regressions were done according

to the methods of Steel and Torrie (1960).

Least square ~na1ysis of the data were done according to Harvey

(1975).

1

1

o

\

1

1 1

',1

,<> q ()

(

\, ____ .. _____ .. ______________ .,_.~, __ ......... U ... ,_ ...... ..,.MIftI_!l!l;"" __ U ... __ III\!.IfIIR. ______ &&111 ___ -:-__ , ___ _

) B. EXPERlMENT

1. Introduction

A total of 810 observations were made during the trial. Fort y-

five (45) cows were divided in three groups of fifteen (15) cows aJld !

fed different levels of grain (H, M and L). The observations wf{re

made during the 18 weeks following the calving of each cow.

2. Experimental results

a. Hay crop silage composition

\

\

\ 1

\

"

During each week two representative samples of haylage were mixed

together and frozen for later analysis. A total of 50 composite samples

were analyzed.

56

The results of the forage laboratory analysis are presented in Table

3. They are expressed on a moisture-free basis.

The average values are in close agreement with those presented by

the National Research Councll (Loosli, 1971) and by Van Soest (1971 and

1973) • • Table 4 presents,tfte simple correlations between the various haylage

components. lt ls of interest to note that the majority of the.cor,relations

are significant. Most are significant at the level of probabilityd<o. 01).

Acld detergent nitrogen 'appèars to have the lowest relationship with other

forage components.

'\' _________ --.JL-________________ ~ ___ ,~ ___ _

.' . ,

1

1 f .

1

. i

()

-., . ""~<"'~~1"~~~,~ntpAii'\i\WII""~'!I~lI!l;,~r,"I_" •• ___ 3_1"U.'''P!lIIlMkIl

Table 1.3. a

Forage Charaeteristies

..

Variable 9 Dry matter (DM) (%)

/ pH

Crude protein (CP)(%)

Aeid detergent ni~ogen (ADN) (%)

Neutra1 detergent fiber (NDF)(%)

Acid detergent fiber (ADF) (%)

Aeid detergent lignin (ADL)(%)

Cellulose (CEL)(%)

Dry matter disappearance (DMD)(%)

Nutritive value index (NVI)(%)

Digestible protein (DP)(%)

N~t energyb (NElaet

) (Meal/kg)

Calcium (Ca) (%) 4

Phosphurus (P)(%)

Magnesium (Mg)(%)

Potassium (K) (%)

a Means of 50 duplieate samples

b NEI

values were calculated aet

57

f

Drl matter content

Mean Std. dev.

39.77 11. 333

5.08 0.444

19.82 3.003

2.16 0.346

46.86 8.217 .. ",\

38.27 7.628 .. 6.97 1.181

32.86 5.939

36.09 6.662 ~

57.04 1. 069

12.26 2.081

1.19 0.129

1.43 0.160

0.34 0.03'0

0.30 0.026

2.51 0.233 ~

1

~l!

')

il

'"

(

rB.

e Table 4.

DM

pH

CP""

ADN

NDF

ADF

ADL

CEL

DMD

NVI

DP

~

R ~ ~ - :-~ ..... ~-·~~~ài~~f.'~~ ~~~,; .4iAP'~'1":";~~ii,~_.:':',-~, Ab)t •• ti·.~ ';C', "',"~~ , - ~_ ~ , " '" ,

.. '"

a b Simple Correlations Between Hay Crop Silage Component8 '

NE lact DP NVI DMD CEL lifL

.42** .37** • 57**f .58** -.60** -.31*

-.78** -.78** -.84** -.85** .82** .69**

.88** - .99** .91** .91** -.90** -.80**

"

ADF

-.53**

.79**

-.89**

NDF

-.44**

.80**

-.88**

. 19n •8 . '.24 n. s. . 250 • 8• .250 • 9 • -.30* -.31* _.24n • 8. _.lSn . 8 .

-.97** -.91** -.97** -.96**- .95** .84** .96** /"

-.98** -~90** -.97** -.97** .97** .91**

-.94** -.7,9** -.83** -.83** .83**

-.94** -.90"* -.98** -.98** W '\0>

\95"* .91** .99**

. 95** .92 **"

.90**

a Means of 50 samples

ADN'

.27n • 5 •

-.28*

.39**

#

b Corre1ations are 8ignificantat (P < .01) (**) for r > .36 and (P<.05) (*) for r > *a,.~

n.s. ~ non 9ignificant

\

CP

.39**

-.78**

ç

.~~ \~~~~

-....

pH

-.46**

1 ~4 ,. { ~

, j, l

). 1

J ..

\.Tl 00

59

el b. Grain composition

Each time a haylage sample was taKen, a grain sample was set apart

and frozen. Therefore a set of 50 grain samples was also analyzed in

duplicate.

The results arê presented in Table 5. They are also on a mois ture-

free basis.

Table 6 presents the simple correlation between these grain

cpmponents. These correlations, on the average, are lower than the ones

we previously encountered for the haylage components. However, it iti

again the acid-detergent nitrogen which has lower correlations with other

grain characteristics. !

"

;-- .

o \~

l'

60

Table 5. , a

Grain Characteristics

Dr! Matter Content

Variable Mean Std. dev.

DM (%) 86.57 3.898 ,

CP (%) 17.55 1. 793

ADN <V 0.78 0.149

NDF (%) 24.52 4.483

ADF (%) 9.67 1.648

ADL (%) 1.84 0.355

CEL\ (%) . 7.88 1.853

DP (%) 11.41 1. 598

NE laet (Meal/kg) 1. 73 0.042

Ca (%) 1. 29 0.225

P (%) 1.44 0.341

Mg (%) 0.39 0.081

K (%) 1.15 0.2j

\ '

a Means of 50 duplicate samp1es

b NElactva1ues were calcu1ated

..

)

\

fi. "'",riÎ!l~'ii9:~ , ;<-, 0 ",,' 0, __ '~"ltr:.,.,.,._: .. ,,;.,;/.~ . ~"' .. :'.!i'W?t.t~':. ~:.' -' ,: i If tian ,.,..44.... 411$$' $ m * cga "'"~ ,~ ... -'

/'

" ----1:>

o

".

Table 6 •

.le

DM

CP

ADN

NDF

ADF

ADL,

CEL

°DF

• a b Simple Correlations Setween the Grain Components

NE 1act

DP CEL ADL ADF

-.64** -.61** .78** .59** .83**

.57** .99** .24* -.55** -.64**

" .59** , • 32* ~ _.OSn.s. -.66** _.26n . s •

./

-.56** -.50**" .93** .50** .90**

-.66** -.64** .91** .62**

-.97** -.52** .37**

-.44** -.48**

.54**

a Means of 50 samp1es

e

NDF ADN CP

.83** _.23n•s • -.62**

-.50** ~ .39**

_.12n. s.

/, b Correlations are significant at (P<.Ol) (**) for r >.36 and (P<.05) (*) for r >.28.

n.s. Not significant

/ ...

".

'"

Yf/I. (l\

~

_ ~_-" _ ~J >J"I~ ;'.Lr *_ ......... ~~~~f~.J:J....:I.~~ .... J ..... ~,., __ ................. _ .... ___ _

[ lU l1W

62

Table 7. 1 a

Overa1l Means of the Raw Experimental Data

Standard Variable Mean Deviation ~SD}

Weight (kg) 572.81 52.562

Metaholic Weight (kg BW· 75 ) 116.99 8.133

Weight change (kg/day) -0.19 2.162

Milk (kg/day) 29.15 17.479 "'-

FeM (kg/day) 27.63 6.755

Fat (%) 3.73 0.,929

Fat (kg/day) 1.06 0.301

Protein (%) 3.13 , 0.381

Protein (kg/day) 0.90 0.216

Grain intake - wet basis 9.88 3.007 1 (kg/d~y)

/

(' Haylage intake - wet basis 26.73 9.309 (kg/day)

a Means of 810 observations ,

/

ci 1

() / /

'1 \

;

'J

~ •

/

()

\

III.' l at III Ji 1212$

c. Cow'characteristics

The overall means of the cow chgtacteristics during the trial ,

are presented in Table 7. Weight'components Jre expressed either as

body weight, metabolic weight (Bw· 75) or average daily body weight

change. This last factor reveals that, on the ayerage, cows during the,

trial (126 days) lost 0.19 kg of body weight per day or 23.94 kg for the

period.

The input is represented by the grain and haylage intakes

efPressed ~n a wet or as-fed basis. 1

The output ia reflect~d by either the amount of milk produced,

FCM, fat and proteln or the fat and protein percentages.

d. Group characterlstics . "

63

To evaluate the effects of levels of grain fed, it Is worthwhile to 1

look at the dry matter intake (DMI) of the three groups of, cows and Its

effect o~ body weight.

Table 8 presents these data:

Table 8. 1

Average Dry Matter Intake (DMI) (kg/day) and Body Weight (kg) over the 18 Week Periode

GROUP Variable l' H M

a Grain" DMI 10.70 (3.04) 7.96 (1. 59)

9.~.02) 10.56 (3.07) Haylage DMI

Total DMI 20.07 (4.14) 18.52 (3.4Q)

Bo~y "feight 572.59 (54.32) 573.08 (58.25) ) i J

a Value in parentheses Is the Standard Deviation\ '

..

L

7.00 (1.63) \

11.12 (3.12) "-

18.12 (3.23)

572.83 (43.23)

.[

~ -- --..-..~ --,

\ 1

l' 1 0 1

Cî

.. """ 11& iilSCII4US PNn iP2i.IIUdtlitltlk • 22 i!Jk"" '.: QI UM l dtl tkÇta

To visualize more accurately the evolution of these factors

in th~ group, threJ figures were prepared. These show the weekly

average DMI (15 cows) of the three variabl~s, Grain~ HCS and total

DM as weIl as body weight. Figure 1 presents group H, figuttt2,

group M and figure 3, group L .. AlI the values included in these

figures are presented in Appendix Tables 2, 3~ 4 and 5. 1

Note firat that the grain intake levels followed the expected '.

pattern and plan of the trial, secondly haylage intake increases as

the grain leve1 decreasés: group L > group M > group H for;haylage

DMI. The third'aspect of these figures ia the evolution of the total

DMI which follows the pattern of the grain DMI. In other words, as

grain DMI increases, the intake of total DM also increases. The fourth

point i9 the body weight curve that has a different pattern for each

group: the higher the grain intake, the more the cow lost body weight , /

at the beginning of the lactation. This could be related to a

lower rumen fill due ta the higher rate of passage of this high grain

ration. However the loss was recovered faater for the li than for the ,

M group and the L group. The L group still not gaining weigbt at the .. end of eighteen w~7ks.

'..,

1

, .. L.; li

64

\

~~~ •• IJIU.lbJ.UlWaJ=a;_"ul a»ii.AU II 'gast.III_11I 1 a.

.)

jj,

,... Ji ........

.ft CIl oU 1=1 H

k CIl oU

fi ~ /:1

()

1 1

1

Figure 1. Effect of Week of Lactation on Grain, Haylage and

\

Total Dry ~tter Intake, and Bodr Weight.

G'J:oup H ... - ~tal intake ____ -'~_ grain intake

. - ."t. - haylage intake

Iii IF.. body weight

r~" iJ • ! '~-~(

25.0 -

20.0

15.0

10.0

5.0

. ,

0.0

o 3.

. .

, ,

6 9 12

\ Week of Lac tation

'\'

' .. E&21GiBt ]_

#'

15

1

~

~

18

65

800.0

700.0

660.Q

620.0

580.0

540.0

500.0 \

\ \

-Ji ........

oU .c ~ CIl

:3: >. 't:I 0

SQ

"1 ... ~ • • II. _.111 IIZR41111.1 lit'.u'.'I ••• H 'lfIIiI"'i ••• 1I112t1S_a .& •• III.rIIIU ••.••• r •• I ••••• ' •• I •• _._111.11_3 .. _IIJIIILII._ ......... _ .. \ • '. ':, • , ~ .~.. • ~ .. t ~ __ "

, "

, 66

l e ,

t Figure 2. Effect of Week of Lactation on Grain, Haylage and ,-

Total Dry Matter Intake, and Body Weight. ,

1 Group M

- total intake t,

r --..---- grain intake

.. _---- haylage intake _. body weight ._. ,

, ! '1 ~ Î 25.0 i L' aoo.o If

r' " J " f" t ~ ~ , t, i

"

20.0 l ' 700.0

"" )~ ./ "

,... 660.0 bO ~ 15.0 /

,... - ~ dl , ~ -\ t'li ...,

l ..., "" ,t:

, ' .s ., J.o

~. 620.0 cu lU ........ _.,,,.-'. ./., ~ ...,

,.,. ... , # /1>-> ..., ..... ' ~ . .,/ ... , '0 ;il! "'. ./

0 10.0 ~

::-. ,. ~ .. / J.o , -Q Il

/ .'--• /~---~ '~- ... /", /"" ....... L 580.0 -----~ / - -~ <......,

" \

5.0 ff

540.0

\ 1:1

0.0 500.0

0 0 3 6 9 12 ' 15 18 ..

Week of Lactation \ '-

" \ -

è'

f

l l l

~

() ,

Figure 3. Effect of Week of Lactation on Grain, Haylage and Total Dry Matter Intake, and Body Weigbt

·1 25.0

20.0

,... ~ '-' 15.0 QI

,:.1 CIl 4J ~ ~

... QI 4J 4J

~ :>- 10.0 ... j:l

*'

5.0

Group L

-----

@

total intake grain intake baylage intake body weight

~" j. ~ J

~

/ ......... _ .. __ . ., . . '."., .~ .~ " ., ' .. """'._. .,;

• 1 1 • "'-..ce. "",... --- -..... ....,.;..,,~ --- ' .)

;. --' " ~~

.... - ' \

T / " '\ .---"1/

\

800.0

700.0

660~0

620.0'

580.0

540.0

0 .. O'--__ -i-__ --''---_--'-__ -''''--__ --J,. ____ ...J, 500.0 o 3 9 12 ; l 18

Week of ~ctat~on . \

9 ru. Lda2l~t ~;j

67

l:

J ,

'. ,... :4 '-' " '1

4J ~ ,d

:f ~ p.,

"t:I 0 ~

t,

"

el

• EIbliCU44J l'SOue., tSdilX b El' 1 lU , t.--y 1

metaL

The mi1k production curves of the three groups are presented

in Figure 4. 1

Group L cows fed the lowest amount of grain produced slight1y

more mi1k at the beginning of the trial. However the differences

between the three groups were not significant.

The average dai1y mi~~ production in kg/day and percentages of

fat and protein for group H are 30.29 (7.764), 3.56 (0.926)-and 3.15

(0.373). These data for group Mare 28.41 (7.174), 3.68 (0.859) and 1

3.14 (0.348); and for group L t'he data are 28.76 (7.360),3.95 (0"962)

and 3.09·(0.414). Values in parentheses are the ?tandard Deviatiôn.

D

f,

/ 1

o '

68

, .~

!:[ .• "'·i'f' , ,,-- , ,". ""'~'1i"",_~">,~~~ ,'" • ''',:. ! • g asi l.'1 _d, MU:." si Ml4l(n2j[Jiill.l1.]_."~~'~~"", " <", " 1"0 ", ; .,;' ,-,., ,ë':'·~·. ",~,- ... ",,",",,~î" ,"'-,'

0 J. ... Figure 4. Milk production curves .

iii<

32.0 ~ ----.........

/\ ;,

1 t \

30.0 l )(. _. f!;&.; .. 1 . '-,

1 - IIV' ~ ~ . / , l ~ • , \. ------...... "tI 28.0 - .

- - t 0

QI -.J:IO

tII ~ ,~

QI

~ 26 O· • r- ... ... -s::

0 ...t ~

1 tJ =' 24.0 r "tI •• 0 ~

t\4

0 a fa:<

22.0 l, 1 \ , 1&

20.0

1 2 4 6 8 10 .u / Post-calving-Week Number -..........

'7:"7 7 rmFSMf'f'f*iM t ...... ,."" ... &1i"'5tCa'"M · ... ,U".U,le-e?te;..,''frtl'fw~~~,_"

;;

---... __ . Group H

Group M ~v

Group L

X

14 16

"

18

a­\Q

,

", , I~'

-',

)

()

70

3. Analysis and discussion

After presenting the data for feed intake, body weight, as weIl as

grain and haylage components used in the experiment, it ls now time ta

look at the Interre1ationship between these criteria. , v

At thls point It ls necessary'. ta say that the ana1ysis of the

data has shown no difference for the diffe;ent periods or weeks or

group of weeks. Therefo\e the resu1ts are presented based on the mean 1

of the overa11 periode

a. Group and parity effects 1

Group effects refer to the levels of grain fed: H, M or L. Parity

effects refer to the age of the cow expressed as whether she is in her

firs~lactatlon or older.

Month of calving was also studied but was not significant.

These an~lys~ were performed using the method of 1east square

. analysis.

1. Wet hayl2ge intake ... The overa11 mean intake of wet haylage for aIl groups (i.e. as

';)

fed basis) ls 26.73 kg/cow/day. The analysis of variance (Appendix ':;' ~

Table 7) shows a sigdificant (P<.Ol) difference for both group and

parity.

The following table lists the least"square estimates and their •

~ differences.

'\.,

l,

)

---..

1 1 ~ , J

1

,

l'

...

,

0

.. ~

Table 9.

lJroup:

Least Square Estimates for Wet Saylage Intake (kg/day) (±SD)

H: - 3.29; M: 0.65; L: 2.64

Differences: H-L: 5.93 ± O.692a

M-L: - 1. 99 ± 0.692b

,If?

R-M: - 3.94 ± 0.692a

Parity: _Reifers: - 1.58; oldettcows: + 1.58 ,

Differences: Reifers older cows: - 3.16 ± 0 .. 527

a, b Values bearing different superscripts are significantly different (P<O.Ol).

'\

~herefore Group H consumed significantly less wet haylage t~an • b

either Group M or L. Also the heifers 'cons~ed significantly ,

less wet haylage than/older cows • 1

iL Dry hatlage inta~

The overall.mean of dry hâylage intake is 10.35 kg/cow/day •.

The analysis of variance (Appendix Table 8) show~ a levei of "

--significance fo~ group and parity at the q.l level. The following

table"gives the leàst' square estilllateB.

'. '

. ,

~ " ,

,) ...'

71

..

,~'

, ,

!

, '

o

Table 10. Lea.- Square Estima tes f'~r DrY4aylage Intake (kg/day)

Group: H: - 0.91; M: 0.29; L: 0.62

Differences: H-L: 1. 53 ± 0.388a

, b

", M-L:. 0,33 ± 0.,388

\ 0.388 b H-M: 1.20 ±

, Parity: Heifers: - 0.57; older cows: + .0.57

Difference: Heifjfs.,...- ~lder cows: - 1.14 ± 0.295

a, b

.,'"

Values bea~ng different supe-rscripts are significantly.different (P<0.05)

) The voluntary JConsUlllption of haylage dry matte-r shows less

differénce than the wet haylage, the level of significance is lower

and the difference exists only between Group H and L.

~ ii1. Ca1culated hay1age NE intake

Tbe Ol·graU mé"an of calculated haylag~ NE intake ia 12.63 } 0

4

Mcal/cow/day. The analysis of variance ~hows no significant

difference fo~ either group or pari~y (Append1x Table 9).

. ,

. J

1 1.

72

\,

Table 11. Least Square Estimates for Calculafed Haylage NE Intake (Meal/day) (±SD) '-

.,. Group: H: - 0.85; M: 0.50; L: 0.35

Differences: H-L: 1.20 ± 0.630

\: M-i.,: O.l~ ± "0.630 ,

H-M: - 1.35 ± 0.630 .. Parity: Heifers: 0.68; older cows + 0..68

Difference: Reifers'i,.. older cows: 1.36 ± 0.480

iv. Fat-correeted milk production

The output was also tested by least square analysis. Thé

analysis of variance appears ln Appendi~ Tabl1 10. No significant , \ .

differenees ~ere found bet~een the groups;~owever, a highly

Sign~ant difference (P<O" 01) was revealed for parity. ~ Analysiè

of variance for periods has not shown any significant differ~ce. ~

Table 12:. Least Square Estimates for Fat-Correctea"-, ' Mi1k (FCM) (kg/day) (±SD)

, Group: H: 0.71; M: - 0.37; L: - 0.34

Differences: H-L:

M-L:

H-M:

1. 0.5 ± 0.713

0.0.3 ± 0.713

1. 0.8 ,. ± ci.713

Parity: Reiters:, - 3.74; older cows: + 3.74

Difference:"" Reifers - older cows: - 7.48 ± 0.543

.. .

..

, 1

lt can therefore be coneluded that the level of, grain gave no - 1

s:Lgnificant effect on the level of FCM produced.

1

/

73

•

•

-.

u ,

b. Hay1age intake and correlation with hay1age components ,

In an attempt to eva1uate the factors exp1aining the Nariation .~

in forage intake, the correlations between hay1age DMI, expressed .

as the average daily intake based on 810 observations, and the . ~ .

hay1age comppnents of each of these 810 observations were ca1culated.

The resu1ts are presentèd in Table 13. The ~esu1ts show an , t

a1mostbconstant re1ationship between hay1age D~I and the forage

components. This is expected because Table 4 has shown a constant J <: .

very high correlation between the hay1ag~ components. Further the

810 observations of intake are based on Sp hay1age samples and it i8

predictab1e that the correlations of Table 13 be ,so .c10se~lated.

The grain DM! is a1so corre~ated~ith the hay1age components. ~

The level of relat~onshi~is -lower. but constant among the factors. • 0

Two other factors are presènted in Table 13. Grain DMl is

negative1y correlat~d with hay1age DMI while metabo1ic 1

is shown to be positive1y corre1ated with hay1age DMI.

both metabolic welght and body welght were, evaluated:

wéight (MW)

Note that II'

thelr

74

correlations with hay1age DMI are very slmi1ar. ,

A 1eas~ square ana1ysis .

1 was performed utilizing the group, the parity, the grain DMI and either

MW or BW as ~actors. The results showed a very slig~t advantage for

MW, the unexplained variation being smal1~r by .000344. Therefore

either one or the other could have been chosen. Howeyer, MW ls , f

retained based on Crampton ~ al. (1960) and Donefer (1966) where this

"expre!"sion showed less vl}riability in expressing the voluntary intake.

"

)

,

, ,

\

\

o

.,_" 1

(

/

" fi

Table 13. q. - ,

Simple Correlation between Average Haylage DM!, Average Grain DM! and Haylage Components a b . .

f!r. Dry matter intake (kg/day)

Var'iab1e Hay1age Grain-

DM .53

pH '\ -.51

NDF -.52

ADF ) .. \ , -.52

ADL . -'.51

CEL o -. ~3

DMD .?3

'NVI • 53

DP "-

.'52

NE" \ 1act • 52

Il '0

train -DMI (kg/day) -.40 , .

MW (kg) .28

\

a

b Correlations based on 810 observations

r significant at' (P<.01) when r > .095

, ...

" '

-.11

.12 !

.18

fi .17

.17

.16 fi

-.16

-.16

-.14-

-.16

.32 •

,)

1.. u

.. d

75

l ,

, ,

,

1 r

,

c. Regression analyais ,

The backward elimination technique was used to evaluate' the ' .

contribution of several factors in exp1aining the variations observed

in haylag~ intake, expressed as either wet, dry matter or NEI • act

76

The tested factors were the following: metabolic weight, grain DM!,

" a haylage DM, pH, ADF, ADL, NDF, I/solubles , DMD, NVI, CELL, estimated

1 digestible dry matter, Ne1act and ADL/ADF.

, As the mi1k and the FCM production are not different a&ong the three "

groups and as there is no difference a~ong the periods, milk was eliminated 1

soon in these regressions. \ '

The factors r~tained in the regression equation ~o be pr~nted aIl

significantly (P<.OS) affected the haylage intake.

1. Wet haylage intake

Only. one set of factors' w~s observed to signif~cantly af·fect the 1

haylage intake value expressed on the as-fed or w~t basis. These two 1

factors are the MW and the grain DM!.

\

Table 14. Regression on Wet Haylage Intake (Y) (kg/day).

L~~egreSSiOn ~ ....

Y = 3.21 + 0.281 (MW) - 1.09 (G)

« MW = mètabolic weight in kg. G = grain DM! in kg/day.

l '1 * , ,

, .

The R2 for this equation indicates'that 66.1% of the variation 1a

unexplained.

a . . l/solubles is equivalént to"1.1 (100-NDF).

" ..

l

'"1('~~ilt~~,.e)J",MZMll!P.JJIl C ...... u:a"'_;~"M'!II, lM iJtII' •• hA!J(UlSi •• tMlr_ ••• !'

77

H. Dry haylage intake

Several forage components affected the haylage DMI. In fact ehese

a11 exp1ain about the same level of variation, ~s might be exp~cted

from the co~lations presented in Table 13.

Table 15- presents 'these regress ions.

Table 15. Regression on Dry Haylage Intake (Y) (kg/day).

Regression

Y = -6.07 + 0.168 (DM) + 0.114 (MW) \

Y = 16.97 - 3.35 (ph) + 0.119.,(MW)

Y = -5.75 + 0.175 (DMD)+ 0.113

Y = 6.2& - 0.146, (ADF)+ 0.112

DM = haylage % .DM pH = s"ilage pH ADF = silage ADF (% DM)

(MW)

(MW)

- 0.451

0.455

0.433

- 0.429

.. DMO = silage Dry Matter Disappearance (% DM) MW = metabolic weight (kg)'

G .= grain DMI (kg/day)

R2

(G) 5~.3

(G) 54.5

(G) 53.4

(G) 52.4

! The best equation for the évaluation of ~aylage DM! is the one

involving the DM content of the haylage, when considered together \

with the grain DMI and the metabolic weight. However, 43.7% of the

variation 1s sti~l unexplained.

From the above equations it can be observed' that an 1ncrease in

1 DM content of the hay1age .J.mproves the consump,tion. .The following simple

'regression e4uation y = ?499 + 0.193 x (Y = dry ReS intake (kg/day);

x = RCS % DM [Std error: 1.681] ) a1so agrees with Jackson and Forbes

.' . (1970) and Larsen (1975). From our data no plateau océurs between

25 and 55% DM.

/

, ;'

,,\

\.

'," ·"'i·'j1'J!f'i\.,"'!"';;,"~~m~~~~~.~"J.II!_~~.:'."'_~J •• \L".I,aau$_al_11&;&

o

It is also shown that an increase in pH adversely affects the

haylage DM! which is in agreement with Gordon ~ al. (1961). In this

study pH and DM content were neg~tively correlated (r = -.46) but both

2 seem to affect hay1age DMI to the same exteht, .~he R being ve1:jY

close.

The last two equations presented haylage DMI related to DMD and

ADF. These two factors contribute equally in the explanation of the

variation in haylage DMI. The first equation presents DMD, which is

u~ed ~n the calculation o~ the NVI. Either DMD pr NVI eou1d have been 1;

used in this equation, both contributing at the same 1evel in the

e~planation of the variation in haylage DMI. Finally DMD was ehosen

• for its simp li ci ty , the value being the result of a simple in Y.ll!:.9.

technique (Donefer et al. 1966).

The last 'equation showed ADF content being related to hay1àge DMI.

This finding is surprising beeause ADF is usua1ly related to digestible

dry matter (DDM) content rather than vo1untary intake (Van Soest, 1975

and Rohweder et al. 1976). However, our fora,ge, which was eut at a very

early stage, ~as of high quality for the most part. Also we used on1y

one speéies and the forage was aIl ha~ested during the same year.

Therefore a very high correlation existed between NDF and ADF

(r = .96); they were also highly correlated with the NEl tvalues , • lic

78

(AI?J, r = -.9,8 and NDF, r = -.97). Whén eorrelated with hay1age DMI, they '\ . .

both showed a correlation of -.52. T~erefore we ean say that both were

of equal value for eXPlaining~~ ~var1ation of hàylage DMI, but • 1

1 \

statistically ADF was very slightly more valid in our stuqy. However,

bath could be used with a very amail error involved. 1

..

\

\ - V' ' '

. ' p',tr.·li<fi,r~l,~~~l[tIJ~~~~"_ •• QIJ._.'''.'"I.;:.iblllll.l!!.nlilT_l._

"\

( )

"". ;0

, ..., ,

Ther~fore the most important single factor 18 the DM content of ) . /'

the haylage in association with the MW and the grain DM~ ,

No combina tion of any of the other analytiea.l fac tors showed

improvement in the R2 ~alues. ()

iii. Ca1culated hay1age NE intake ;

The evaluation of the haylage NE intake involved _the same factors

as in thé eva1uation of hay1age DMI. However It is of interest to note

the increase in R2 as showed in Table 16. /

Table 16. Regression o~ Haylage NE tntake (Y) (Meal/day).

. ' Regression R2

Y = - 14.40'+ 0.368 (DM) + 0.145 (MW) - 0.5821 (G) 73.1

Y - - 14.58 + 0.409 (DMD)+ 0.140 (MW) - 0.531 (G) 72.6

Y = 13.78 - O!349 (~F)+ 0.138 (MW) - 0.517 (G) 71.9

DM = haylage % DM .. MW = metabolic weight (kg)

G = grain DM! (kg/day) DMD = 8i1age DMD (% DM) "\

ADF = 8i1age AnF (% DM) . ' b

Wlth the regression presented in this table and in previous

Tab~e 15, it ls ,relevant to note that the factors invo~ved are the same

ones but thè unexp1ained variation has dec1ined from 45% to a1most 25%.

These flndings lead to the çone1us1on th~t these factors are more

related to ihe haylage energy<intake than the haylage'DM intake.

To eva1uate the enersy status of these cows,'the next section will

evaluate the consumption in relation to the calculated requirements.

79

1 •

î f

. \ -,'j ;:\,1I:'~"~._"u'~~"""'.;i",.~~JJ!_" ___ (lSt.J_JMlWiiJllJ!llMtMçq;",

_ f

..

80

d. Requiremen"e versus. intake

Th~ com~et~ picture of estimated requirement vs calculated . . .

intake for the three groups of cows is presented in Appendix Table

11. ' The statua of the digestible protein, NEl and severai mineraIs , act

and mineraIs "ratio is shawn. these values represent the complete

ration components expressed either as required or consumed per day.

Of interest, it is ta be noted that NEl t is the only single l' a~

factor which shows a requirement higher than the amount ç?nsumed

during the trial in two groups out of the three. Digestible protein, ,,,

Ca, Mg, P and K were consumed in amounts higher than their requirement.

The ratio of K over Ca + Mg seems to be !pw. Two factors cou!d explai~

this 8ituatio~. First the consu~ption of calcium was about 2.6 time~

higher than the requirement and second, the requirement·of K/(Ca + Mg)

calculated from the NRC (L0p,sli, !971~ seems to be high if compared with . '/

other sources of informati~n. For example, Buck (1974) indicates

the recommended ratio i8 between 2.2 ta 1.0 and 1.0 ta 1.0. The

observed ratios were between 1.03 and 1.11 which are borderline and

could explain the lack of ~losSi~ess of certain cows during the trial.

Therefore the most critical single factor i8 energy and this is

why Figure 5, 6 and 7 showing the relationship between NE! t . Be

consumption and"requirement were prepared.

Figure 5 shows group H in which the high 1evel,of grain fed

allowed these cows to consume more energy th~n they required. ~his i8

~xpressed clearly by the continuous gain in BW after fivé weeks of

lactation. o

1

\

-,

l ~A •• '.!Ja_"I ••• II"'.a=2UJ1I'M~.I' __ .I14. 11111 J hi iAi Id 1 Jllt.a JUI1! .: 1;10 ..

---, .

'.

<:;1

• Ii

o

Figure 6 presents the M group where the cows seem to a1most 1

perfect1y eya1uate their consumptions in relation to their

l requirements. lt i8 to be noticed tha t the cows consumed thf!ir

requirements only at the ninth week whereas cqws on group H did the same

at the sixth week.

For the group L presented on Figure 7, the situation ia very

critica1. For the complete period the cowa consumed 85% of their ~

requirements; theY,never ate enough energy to cover their needs.

Table 17 presents the b9dy weight change.

Table 17. Pattern bf Body Weight Changes

Average a

/

Group Weight loss b Weight gain c ,

a

b

c

H , 44.96 38.49

M 38.25 26.15 ...

L 51. 70 ,5.24 b

, 15 cows average per group

weight 10ss from calving to minimum post-calving weight.

weight gain from'minimum post-càlving weight to the next­maximum weight

. \

.1 ( .\ \

\

""'-

o , '-

81

, ,

o

82

, . Group L cows lost body weight more serfously than the other groups.

After they had reached their'lowest body weight, each group regained

weight proportiona-tely to the amount of grain the cows were receiving: >'

group~ H > M > L. In fact, group L cows regained very few ki10grams

1 \

and the pattern of figure 3 shows that they are almQst stable at

their low level of body weight.

Appendix Tables 12 and 13 present the total NE requirements and lact

consumptions over the 18 weeks for the three groups. • .(> ,

In an attempt t~, exp1ain these variations in energy intake which 1

are nef1ected in body weight lO~8es, the concept of calortc denstty

regulation (II.A. 3. b. )" was appl1ed ,to the data. Table 18 shows the'­

data required for the calcu1ation of the. total NE intake pe? kg mt 75

and Figure 8 presedts the graphica~ firuiing. " ..

, "

'\, \ ,-

"

:~ 1 iIj

... ~ ~~ ~ ,

-',

p ,. '! '

~

l,

(1

(

'"' ~

Figure 5. Effect of Week of Lactation on Net Energy,Required~ Net Energy Consumed, and Body Weight !'

40.0

30.0

Group H " _w 6

.. _----

/ ' .. ". •

1 •

1 #

1 . "

NE required NE consumed body weight

.'t 'i:}

....

'" ""--1--' # ..

",~ / , ' .. __ # .,

~ -' 1 r-I 111 20.0 --' ~ , '

.&.1 cJ 111 r-I

~ ~

10.'0

0 • .0 o 3 6 9 12 15 18

Week of Lactation "

.lI

LJ st L ,%tL!E 21111

83

/

660.0

,..,. tIO

620.0 .w ....... .... ~ oI"f QI ~ 1>'1,

580.0 -g ~

540.0 "

c

500.0

.' ,

.1 {

" J

J

~o {

, '-"~Ii'\~~~~~)ii !l$!pm~"'''''~ __ ~B"i'JiI\ll~IlII.1mJIt'ffll~.'IMlNi\l.4'_M'',~'

'"' Ji -r-t ct! 0 :E ...... ... 0 ct!

r-t

~ :z;

-o· ., "

40.0

30.0

20.0

J.o. 0

, Efhct of Week of La~ tation on Net Energy Requ!red, Net Energy Consumed, and Body Weight

Group M

------NE required

NE consumed. body weight

..

..

l

....,'

,.,

~

0.0~----~--__ ~----__ ~ ______ ~ ____ ~ ______ ~-4

o 6 9 12 15 18

,..

11

J _

Et fi

54~'.OJ .J

500.0

'.

-..

, 1 ,

o

Pigure 7. Effect of, Week of Lacta.tion on Net 'Energy Required, Net Energy - Consumed, and Body Weight

GrollP L

___ NE requireq -- ____ • NE consumed ---_____ body weight

.' 40.0

30.0 / 1

-00 .!II -r-f co (J 20.0 ~ ....... ~ (J co

r-f

~ ~

10.0

\

.,

700.0

660.0

620.0

580.0

540.0

~ ____ ~ ____ ~~ ____ ~ ______ ~ ____ ~ ______ ~500.0 0.0 o 3 6 9 12 15 18

Week. of Lactation

• ; $~ .. fBjJ~ 1 ilt~z: & __

85

....... Ji -

,

,j'~·":<"'1j-\:·"~,I't,\~"\iI"-","!:',~ .. J"""~l"~;I,~~~_~",~(."",,,,t!l;\'.1P'lIII1"~MJIW,~.II •. __ "..:.

o

~

"'-

Table 18. mtake and Calorie Density •

./ • GROUP

Variable ~Averase of 18 weeks} H M L

Me:.bol~C wt8ht (kg) • 116.96 117.02 117.03

Total NEI

intake (Meal/day) act 30.12 26.79 25.18

Total DMI (kg/day) 20.06 18.53 18.12

NEI

/DMI (Meal/kg) act 1. 50 1.44 1.35

Total DM! {g)/kg MW 171. 51 158.34 ('

15~. 83

NElaetintake (Meal) /kg MW/day 0.257 0.228 0.209

J>

The NE1 intake ranged from 257 and 209 kenl/kg MW/day. These net

1 /.75 values may be slight y higher than the 370 keal DE day per kg body

, . weight suggested by Bull et al. (1976) as being the plateau of energy

~

intake. However the same authors reviewing the literature,found resu!ts

similar to ours. Figure 8 illustrates these data: it can be seen that

the effect of the inerease in grain feed1ng (H group) was to increase 1

the NE content of the total ration consumed (1.35 for group 'L and 1.50

for group H) and this made it possible to improve thé total DM! per kg

MW. ln conclusion the higher the ~E content of the total ration was,

the more DM was consumed per unit of metabo1ic weight •. lt does not

appear that energy intake plateau was reached in this study. \

86

-

1

<~;f"IfI'~<'~.;'lI'>f'\":~\1." ~1!'l!J""'!I!'.~1 III,."l» ;.W· ..... ~ ~Wh .. ew!!<il'!IiiÇ}&;W:1i\II1J~R"i#iiI!\!b,".:~(j ii!#W'C"UIUh J •• u ................... ....".. ... , •••• _,_. , .

.... t 87

Figure 8. Effect of the Total Ration NE on Matter Inta"e 1 ·the- Total Dry ~

180.0

1 -lr'I ,... .~ 170.0 .. H

00 ..:.: -, 00

"" Cl)

1 00 Q)

Cil ~ ,.. Cil Cl) ~

~ s:: H

c;:l., ,.. 160.0 ;::1 <:l 0 ~I ,..

~I ~. M (.!)

~ :>. r-! ~ ..-l, L Cil A • ~

.-1 Cil ~ 0

" E-I 150.0

. . i , , t

l ~

140.0 Î l'

1.00 1:25 1.50 ~ 1.75 \? , " Total Ration

0 NE lact (Meal/kg)

-~

"

.'

\.

""'·'''''''''1~,'{~I~~.~~I!I'IIll'I'''~!I''''''''/JII~~ .. ,Af "::.III .. ~~iY.!!Jl\I""'I_' __ 1

e. Health and reproduc tion

1.J In general the literature reporting results of trials comparing

hay and hayiàge based rations ls very limited in commente on health

and reproduction.

Recently, severa! trials compared rations based on corn silage .. plue hay, corn silage plue haylage and corn silage a10ne. Belyea et al.

(1975a,b)report no diff,erence in the occurrence of mastitis, while there

Q was more ketosls when no hay was fed, more parturient paresie wlth corn

. " . '

silàge alone and displaced abomasum rtoted only when corn silage was , ,

fed with no other forage. Smith et al. (1976) using similar rations

compared the levels of plasma growth hormone (GR) and insuline The diets

had no significant effect on these two parameters.

Everson et al~ (1976) studying semicomplete ration based bn

haylage ad libitum plus grain in different ratios plus 2.3 kg of hay

report no apparent h~alth pattern due ta treatment. The only case of

displac~d abomasum was associated with high grain feeding.

Table 19 shows the health records of the three groups of cowS •

• The data show 16, 12 and 14 cases of disease which necessitated

veterinary assistance, for the respective groups H, M and L. lt 1a

therefore difficult ta associate any disease pattern with the treatment.

.. (

88

,-·0 ..

(

"

o

89

Table 19. Health Statuaa,

c Diaease " H

GROUP M L

Milk fever 1 2 3

Ketoais 2 1 2

Hardware diaease 1 0 0

Disp1aced ab omasum ,1 0 0

Pneumonia 1 0 0

Mas ti tis 5 4 5

Metritis 2 2 1 =

CysUe ovary 3 '3 3

Death lb lC 0

a Number of eows affected

b

c

Pneumonia ~death occurred after the 18 weeks experimenta1 period)

Acute mas titis (death occurred after the l~ weeks experimental period)

'cr

" , '

,1;':­Q

di HI

'"

. .. , ,. t,

\'

:.

, , ..

o

90

The reproductive"status is presented in Table 20. The number of

open, days i1.s 'very high for every group. Even wh en th'e three worst,

cows are taken out, assuming that they could have bllen "trouble cows",

the expected calvlng interval is over 400 d~ys. This' interval is high but l'

comparable with many commercial herds. Howevel' it still remains too

high by most management criteria. Further~ the four cows ~t in calf ,

as yet have been open for more than 365 days. On e explanation could

be the presence pf Zeralanone and Aflatoxin in the high moisture corn

fed dtiring the first half of the e~per~ment. However, this factor may

not fit to the data because there was ~o apparent improvement during the

second half of th: exp~~ment in the number of open days. However the

beat periods of the cows came back to a mor~ normal cycle for most of

them. A residusl effect of the Zeralanone and Aflatoxin could be present

but this is impossible to evaluate.

A second factor which can explain part of this situation is t~e

negative energy balance in which group L cows were found during the

total periode The usual period 'of time for a cow to regain its week 1

postpartum weight ~s about 28 weeks (Everson ~.al., 1976). To return,

to week l weight in 28 weeks a cow must begin to gain weight at

approximately week 8-10 postpartum. This was .ao-hieved by cows in group.

H and M but not by animaIs in group L. Indeed after 18 weeks they \

(L) were still l08~ng weight ~nd this could be why 3 cows in that group

baye been open for more than a year. This could also partially explain .

the higher number of open' days' encountered for that group (L) ~hen the l,

three worst cows of' the group were not included. However, this factor .' " ,

alone ,does n~,tl explain ali the differences in Î'eproductive performance \ ,

" .

1 , 1 1

l i ~

,<

o

JIll " .: _,. 1

becaus'e cows in group H and M ,also have poor reprod,uc'tive records,

even though they were in positive energy balance 'ear1ier in their

lactation.

Table 20. Repr~~uctive Status

GROUP

Variable H M

Number of cows at the ,beginning of the trial 15 15

Nb of cows w!th avallab1e reproductive dataa 14 13

Nb of pregnant cows on 1/1/77b 13

(1 13

Average nb of open days ( SD) 171.9(106.73) 146.9 (51. 29)

Average nb of, open days J

without the three worst cows of each group 122.5(52.67) 125.8(35.80)

a In group H, one cow died of pneumonia In group M, on~ died of acute mastitis and a second

one was so1d for '1ow production and reproductive problems

b

f.".

In group L, one was so1d for udder prob1ems and two ?ere aold for low'production

This date ia 270 days arter the lest cow ca1ved.

Economic aspects

L

1'5

12

l 166.775)

~ 129. 8 ( 41. 23)

91

To use either a least cost formulation or pulximum pro'fit formulation

one shou1d be aware of production response relationships. From this\

experiment lt ls possible to evaluate the link between grain intake,

forage Intake and FCM output.

o .. ~, , .. "

Il

Il

Tlle' 1 relationship between grain intake and FCM cproduc tion ts the

following :' .l') y = iJ.7. 71 +1.15 (X)

where: ~

y~=~g of FCM Pfoduc~d/day and X = kg of grain DM intake/day.

Therefore each additiona1 kilogram of grain pro~uced 1.15 kg of . ..

additional milk. this ls a high leve1 of conver~ion when compared to

the review of Smith (1976) ~here values range from .43 to .80, with

one at 3.00kg additional milk. However. we need to be carefùl when

compBri90ns are made because our experiment covered on1y the first 18

week~of the lactation where the energy peficit is at its highest

levei and when the milk p~tential i9 at tts highest level too.

The relationship between'grain and hay1age intakes is the

y = 13.55 - 0.37 (X)

where:

. y = kg of haylage DM intak1! day and X = kg of grain DM intakel 1 day

SUs equBtlon shows a decrease of 0.31 kg of haylage intake fol" every

kg of grain DM consumed. This value ls in agreemeht with the values

reported in the review (lI.C.3.b.ii!.).

From the&i two equations, data in Table 21 cao be calculated •

. '

Table 21. Input-output Characterlst!cs Based on 305 D~ys

Grain levei (kg)

Haylage intake (kg)

FCM (kg)

..

1000 1500

" 3759 3572

6551 7127

~ti ,$ ... , ~ ___ tt

2000

3385

7702

2500

319'8

8277

92

'I

1

...

, '-

1 _

, "

, "

This tabie demonstrates the relation shown in the two previous

equations: an'inerease in FCM ~roduction in relation to an {ncrease

in grain intake and a s1igh~ decrease in hay1age DM inpake.

Figure 9 prese~ts the resulting income over feed cost (lOFe)

fram various priees for haylage, grain and mi1k. This table shows ,

the fact that, even at an unrealistic high grain price($220!907kg), ,

it ia still beneficial ~o feed grain at a high level when the price 1

received' for mi1k is $10.00/45.4 kg. How~ver, in this trial, the

cows were fed according to,their production: ,cows that produced

more were fed more. lt'is therefore difficult to separate cause and

effect in this re1ationship between feed intake and milk production.

Cows

more

that prOd,e more are fed more; cow~ that are

(Tong et 1.,1976). - . ,

fed more produce J

j

93

,1

,

\,

:X~ ,...

t ~

/

-0-

,\ .

..

..

* 4-1 ID 0 0

~ II»

CIl l'&t

t, t g ~ .... ,!:i CI-

l 0

/-

+160

/

+i20

+ 80

+ 40

o

-20

... = ..... __ ... AP' ......... ,..,.~;-w"""':~-~""'~""'Ii~~~J~-;;-~

/ 9

Figure 9. Response in lOFe vith m11k at $lO.OQ/45.4 kg F~

1000 lSmt ' 2000 2500

Kg grain DM intakè

$/907 ~g-DM Grain

160 160

•

~'

220

Forage 40 ., 20 -. /

40

220 20

~

-~

~

"

'" .t-

Yif ,~

J ~'t ~.~

-i 1 " ~

~~

, .

.' .

\ • • G'

'.J.",lJ{,tt{@ •• JJJlt.J ••.• .q_U!SlHl XIIi_Rl_IIJJ. iII,r.~.t.:I,I; ___ 2Itt iJIUI.'11U:a:yIi •• " .. Nnt ~bL$2 .,.

,.

o

1 •

95

v'. SUMMARY AND CON.CLUSIONS

During the first' elghteen weeks after their respective calving

date, thrèe groups of iifteen dbws each were fed respectively a high, }. l "

medium and low leve! of grain with hay crop silage as the sole

forage in a continuous lactation study •

• t " .During'the trial, the cows, weighing 572.8 kg, produced an ,

average of 29.2 kg of milk, wfth 3.7%, fat and 3.1% protein. The

laverage intakes of haylage and grain, on an as-fed b~sis, were

respectively of 26.7 and 9.9 kg per day. The hay crop sUage had an

average content of 39.8% of dry matter, 12.3% of digestible protein

and 1. 2 Mcal per kg of DM whereas the grain mixture content was " .

respectively 86.6, Il.4 and 1.7.

The hay crop silage consumption (as-fed basis) was different

(P<.Ol) between the groups, the L group.consuming 5.9 kg more wet forage

than the H group. The heifers consumed 3.2 kg less wet hay1age than the

older cows. On ~ dry basis, t~e differences were l~ significant

(P<.lO)for either group and parity. On the basts of hay crop silage , \' 1

NElact~take, there were no significant differences. The production of .• , '

fat-corrected milk was significantly (P<.Ol) d~fferent f~~ the parity,

the h~~ers producing 7.5 kg of F~M 1es8 than the older cows. 'J;here

was no difference in FCM production between th,e three groups of cows. '\ " "

Mos t of the components of the hay crop sUage were high1y

corre1ated (P<.Ol). The haylage dry matter intake was corre1ated~to

almost the sarne extent with aIl fiber components 0i the sUage.

\ ,\

\

, i

.

\ 1

1

1

1

~

, .. : ~

. '~~"",JI"*,},!!.;~e;JJ.I'ii~_,*",,,nnl.tr.'''''_I,''_~MWMt§tP __ ,~~

/

o

, ,

." ,"

Based on 810 observations, the dry nu1°tter content of the silage,

the metaoolic weight of the cows and the amount of grain consUlîIed were

the best f~tors to explain the variation

2 ' = 56.3) or NE1 t hay1age (R = 73.1) ac .

in either dry haylage •

intake. The second bes t

.. factors were, in place of'dry.matter, pH, DMD ot AnF content 6f the

si1age in combination with MW and grain consumption. Milk produc'tion t'

has never reached any significant level in these regressions nar has 1

any quadratic equation of any'kind. ,

When the vo1untary consumption is compared to the calculated '"

requirements, it is evidenced that gx:oup L was underfed, from an enetrgy

standpoint. The fUer mass of the total ration is considered as having

been a limitative factor for this group.

No assaciati9n >between the heaith record~ and the treatments .J~'-''' _

can be sustained •. ,~owéver for the reproductive status a relationship rr'

'Y:' is identified, the group L, energetica1ly underfed, showing a weaker.

situation although the three groups had a11 together very po or records,

this situation being par'tially explained by the presence' of Zeraianone

and Aflatoxin in the,h~gh moistur! corn.

The derived production fùnc;tions are putting a great importance

1

on grain levei showing an Incr,ease of 1. 2 kg of FCM for every ~ of

grain DM consumed. This figure, higher than, the usual ones, can b~

explai,ned by the lI7ell known low 1evei of energy content of hay crop

dlage. Therefore the positive contribution of grain in milk production

,-_is evidenced for even a highly priced grain mixture, when hay crop "

dlage is fed. \

"

96

"N,

"

/

o

,Aerts,

'"

LITERATURE Q CITE[)

{

J.V., D.L. De Bràbander, B.G. Cottyn, F.X. Buysse, and R.J. Moermans. 1974. Comparison of methods for dry matter determination of high moisture roughages and feces. J. Sei. 'Fd. Agric., 25:619.

Association of Official Ana1ytica1 Chemists. 1975. Official methods of Analysis. 12th ed. WashingtJn, D·.C.

Baile, C. A., and J. Mayer. 1970. Hypothalami2 centres: feedbac1ts and- receptor sites in the short-term control of feed intake. ,Pages 254-263 in A.T .. Phi1lipson ed. Physiology of digestion and metabolism in the ruminant. Oriel Press, N~wcastle upon Tyne, Eng1and.

Baile, C.A. 1971. Control of feed intake and the fat depots. J. Dairy Sei., 54:564 •

• ,Baile, C.A. and J.M. Forbes. 1974. 'Control of feed intake

and regulatian of energy b'a1ance in ruminantS'. Phys~ Rev., 54(1):160.

Ba1ch, C.C., and R.C. Campling. food intake in ruminants.

1962. Regulation of vo1untary Nutr. Abstr. Rev .• 32:669.

Ba~mgardt_ B.R. 1969. Voluntary feed intake. Pagea 121-137 .!.n E.S.E. Ha.fez and I.A. Dyer, eds. Anima1,growth and nutrition. / Lea and Febiger, Philadelphia, Pa.

____ • 1970a. Control of feed intake in the regulation of e;nergy balance. Pàges 235-253 in.A. T. Phi111pson, ed. Physio1ogy of digestion and metabolism in the \rumi~nt. Oriel Press .. Newcastle upon Tyne, Engbnd.

1970b. Voluntary feed intake by _ ruminants: modela " and PJ'actical applications. Pages 85-92 in Proceedinge

1970 Cornell Nutrition Conference for. Feed Manufac turers, 'Comell University, Ithaca, N. Y.

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, Be1yea, R:L., C.E. Coppock, and G.B. Yake. 1975b. Effects

of sllage diets on hea1th, reproductoion, and blood metabolit.es of dairf eatt1e. I·J. l)aiÏ'y sc:r.,' 58: 1336.

\ • .' f .. ,' '. ;~\Ii .~~Id\J" .. ,

97

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Bines, J.A., and A.W.F. 'Davey. 1970. Voluntary intake, digestion, rate of passage, amount of materiai in the alimentary tract and behaviour in cows receiving comp1~e diets containing str~w and concentrates in di~rent propbrtions. Br. J. Nut., 24:1013.

Bines, J.A. 1971. Metabo1ic and physical control of food intake in ruminants. Proc. Nut. Soc., 30:116.

______ . 1976. Factors influencing vo1untary intake in cattle. Pages 287-305 in H. Swan and W.H. Broster, eds. Princip1es of cattle production. Butterworths, London.

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B1axter, K.L., and R.S. Wilson. 1962. The voluntary intake of roughages by steers. Anim. Prad., 4:351.

B1axter, K.L. 1962. The regu1ation of the energy intake.

tj

Pages 280-292 in K.L. B1axter. The metabol~sm of ruminants. Hutchinson & Co. Ltd., London.

B1axter, K.L., F.W. Wainman, and J.L. Davidson. 1966. The vo1untary intake of food by sheep and catt1e in relation to their energy requirements for maintenance. Anim. Prod., 8: 75.

Brody, S. 1956. C1imatic physio10gy of cattle. J. Dairy Sei., 39: 715.

Buck, G.R. 1974. Complete rations for milking cows. Ontario Ministry of Agriculture and Food. Agdex 410-52.

Bull, L.S. 1972. A review of factors affecting feed intake

Bull,

in ruminants. Pages 60-69 in Proceedings 1972 Maryland Nutrition Conference for feed manufacturers, University­of Maryland, Maryland.

L.S., B.R. Baumgardt, and M. Clancy. of cAlorie density on energy intake J. Dairy Sei., 59:1078. ~

1976. Influence by dairy cows.

Campling, R.C., M. Freer, and c.e. Balch •• 1962. Factors affeeting the voluntary intake of food by.=-cows. 3. The effect of urea on the voluntary intake of straw. Brit. J. Nutr., 16: 115. , .

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98

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Campling, R.C. 1970. Physieal regulation of vo1untary intake. Pages 226-234 in A.T. Phi11ipson, ed. Physio1ogy of digestion and metabolism in the ruminant. Oriel Press, Newcastle upon Tyne, England.

Chandler, P.T., and H.W. Walker. 1972. Generation of nutrient specifieat~ons for dairy catt1e for computerized 1east cost ration formulation. J. Dairy Sei., 55:1741.

1

Church, D.C., G.E. Smith, J.P. Fontenot, and A.T. Ralston. 1971. Taste, appetite and regulation of food intake. Pages 737-762 in D.C. Church .. ed. Digestive physiology and nutrition of ruminants. O.W.U. Book Sto.res Inc.t. Corvallis, Oreg.on.

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Corbett, J.L. 1969 •. Pages 5~3-644 la D. Cuthberson, ed. International Eneyclopaedia of Food and Nutrition (c1ted by U~yatt, 1973)'-

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Cf~pton, E.W., E. Donefer, and L.E.

I

Lloyd. 1960. A nutritive value index for forages. J. Anim. Sei., 19:538.

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value of feeds., pJoceedings of a Symposium. Gainesville, F1orida, 1972. NAS Washington, 494 pp.

4 ZiOL __ CUM

99

f,

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o

J

Curran, M.K., R.H. Wimble, and W. Holmes. 1970. Prediction of the voluntary intake of food by dairy cows. 1. Stall­fed cows in late pregnancy and early lactation. Anim. Prod., 12:195.

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100

Donefer, E., E.W. Crampton, ànd L.E. Lloyd. 1966. The, prediction of digestible energy intake potentia1 (NVI) of forages using a simple in vitro technique. Proc. Xth Int. Grass. Congo 442.

-----------~ Donefer, E. 1966. Co11aborative in vivo studies on a1fal~~-

J. Anim. Sci;, 25:1227. ~ '-, ~--

Donefer" E., I.O.A. Ade1eye, and T,.A.O.C. Jone~. 1969 •. Effect of urea supplementation bn the nutritive value of NaOH-treated oat straw. Pages 328-342 in Robert F. Gould, ed. Ce1lulases and their applications. Adv. Chem. Sert 95. American Chemieal Society, Washington, D.C.

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---• 1973. Effect of processing on the nutritive value of roughages. Pages 211-227 in Cunha, T.J., chairman. Symposium on the effect of processing on the nutritionsl value of feeds, Gainesville, Fla., 1972. NAS Washington. . ,

, 1

Dulphy, J.-P., and C. Demarquil1y. 1972. Influence de la machine de récolte sur la valeur alimentaire des ensilages. J. Résultats préliminaires. Ann. Zootech., 21:163.

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1973. Influence de la machine de récolte et de la finesse de hachage sur la valeur alimentaire des ensilages • Ann. Zootech., 22:199 •

Esan, B.O. 1971. Ana1ysis of variation due to gédetic and environmental factors in gross mi1k constituents in Quebec dairy cattle. Ph.D. Thesis, McGil1 University.

Everson, R.A., N.A. Jorgensen, J.W. Crawley, E.L. Jensen, and G.P. Barrington. 1976. Input~output of dairy cows fed a complete ration of a'constant or variable forage-tO-grain ratio. J. Dairy Sei., 59:1776.

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!&r~âDook No. 379, A.R.S., U.S.D.A., Washington, D.C.

---------~---~--GOering, H.K., C.H. Gordon, R.W. Remken, D.R. Waldo, P.J. Van Soest, .' and L.W. Smith. 1972. Ana1ytica1 estimates of nitrogen

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•

Gordon, c.H.,/J.c. Derbyshire, R.G. Wiseman, E.A. Kane, and C.G. Melin. 1961. Preservation and feeding value of a1fa1fa stored as hay, haylage and direct-eut ailage. J. Dairy Sci., 44: 1299.

1;.,.,

Gordon, C.R., J.C. Derbysh~re, W.C. Jacobson, and R •. G. Wiseman. 1963. Feeding value of low-moisture alfa1fa silage from conventiona1 silos. J. Dairy Sei., 46:411. . ,

Hang, K.F.N.K. 1970. Factors affecting vo1untary intake of forages by ruminants. M. Sc. Thesis, McGi11 University •

; 1

Harris, C.E., W.F. Raymond, and R.F. Wilson. 1966. The vo1untary . int,ake of spage. Proc. Xth Int. Grass!. Cong.: 564.

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101

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17,,­~ f M

1968. Variability in ad libitum forage intakes by sheep. J. Anim. Sei., 27:159.

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Heaney, D.P. 1970a. Reliability of feeding value indices for 1

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1

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102

1 (

"'\"-f~~J~"!lJl.,~.~_~,!4I""'.O_.'I_U.I;U._i' •• "'Ili

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Lamb, ~C., G.E. StoddaTd, C.H •. Micke1sen, M.J. AndeTson, and D.R. ~~a1do. 1974. Response to concen~rates containing two .. ' perc~nt of protein fed at four rates for complete lactàtions. J. Dairl,Sci., 57:811.

()

Larsen, H.J., E.L. Jensen, and R.F. Johannes. 1971. A comparison of hay1age and wilted grass silage plus hay in the dairy cow diet. Univ: of Wis. CALS. Res. Rep. A225l:- Il pp.

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, , Larsen, R.E., and ~.M. Jones. 1973. Effects of different dry matter

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, Marten, G.C. 1970. Measurement and significance of'forage

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., Moxley, J.E. !975. ~Pérsonal communication.

. ~ _ U 11

103

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',~ .. j*,f{fJl_2_k_ li ... , SM.,PAn _ad _& 1 IL. JUil 111111111111.' ••••

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Murdock, F.R., and A.S. Hodgson. 1969. Input-output relationship of cows fe9 two types of roughage and two levels of concentraté during complete, lactations. J. D~iry Sei., 52: 1961. ~. !

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. 1973. Optimum feeding of dairy animaIs for meat and milkt

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Effects of low fluctuating Part III. Cano J. Anim.

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1973. Influence de quantités ingérées ~hez

C.R.Z.V. Theix-

Richards, I.R., and K.N. Wo1ton. 1975. A note on the prediction ot sUage intake by catt1e. Anim. Prod., 20:425.-

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?

104

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Stallcup, O.T. 1975. Factors affecting feed intake in lactàting dairy cows. Pages 101-1111 in Proc.' 1975 Arkansas Nutrition Conference for Feed Manufacturers. Univ. of Arkansas.

\

Steel, R.G.D., and J.H. Torrie. 1960. Principles and procedures of statistics. McGraw-Hill Book Co., \ Inc., N. Y., 481 pp.

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! \ ~ ; • and L.A. Moore. 1965. New chemicals methols for analysis

of,forages for the purpose of predictirig nutritive value. 9th lnt. Grass. Congo Vol. 1:783.

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forages. Proc. National Conference Forage Quality Evaluation and Utilization. Nebraska, E-l.

1

106

Webster, A.J.F. 19~6. The influènce of tne climatic enviro~ent on ~ metabolism in cattle. Pages 103-120 in H. Swan and W.H. Broster, eds. Principles of cattle product~on. Butterworths, London.

Wilkins, R.J., K.J. Hutchinson, R.F. Wilson, and C.E. Harris. 1971 . The vo~untarY,intake of silage by sheep. I. Interrelationships between silage composition and intake. J. A~ric. aci., 77:531.

Zi~er, E. 1971. Factors affecting silag~ fermentation in silo. lst lnt. silage Res. Conf. National Silo Association. IOWA: 58. ,~

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/ APPENDIX TABLES

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e ; Appendix Table 1. Cows and Heifers RatinS

1 1

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GROUP 1 H 11 L i

Cows 1 85 82 83 , <,

97 ~ 91

98 0 99 94 . 103 101 99

,110 • 107 101

111 109 105

115 109 107

117 111 109

119 111

112

113

121

Heifers 2 5.9 - 5.3 - )2.4 ... '\

+ 0.9 . - 1.4 + 1.1

+ 1.0 + 1.Q + 5.9

+ 2.2 + 1:5

+ 2-.9 \ + 2.8 ,1. , \

+ 12.9 + 4.6 , +10.6 il

Total 15 15 15 ~ 1

"

1 - 0 '. mlAS cow rating j 2

, , Expected average deviation from themean (R.O,P.) .,

, ., 1 1 !

1.

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e • • AppendiX Table .2. Baylage Dry Matter Intake (kg/day) over Weeks a

Week GrouE B Grou:e-M- / Group L Number Average DM! Std dev. Average DMI Std dev. Average DMI Std dev.

1 6.47 3.046 7.10 1.849 7.21 2.263

2 6.45 1.871 7.82 2.585 7.78 2.470

3 7.22 1. 748 8.61 2.663' 9.96 3 •. 275 j

A 8.51 3.is4 10.70 3.119' 10.57 2.454

5 8.~} 3.395 9.75 2.246 10.98 2.861

6 9.73 2.909 9.44 ' 3.597 10.36 2.952 ~.

7 9.38 3.114 10.18 2.736 11.33 3.382

8 10.14 2.766 10.71 2.788 11.48 3.419

9 9.89 2.139 11.53 2.543 12.82 3.579

la 10.02 2.388 10.54 2.348 12.28 3.415

11 9.32 2.289 11.60 2.603 12.30 3.299-

12 9.24 3.056 11.87 2.403 12.17 1.057

13 10.36 2.803 Il.40 2.227 12.30 1.908

14 10.80 1.995 11.97 ~.~5 11.6.3 2.171

15 10.71 2.646 ' 11.24 2.776 12.59 2.801

16 Il.12 3.647 11. 54 3.358 11.60 2.778

17 '10.68 2.978 12.82 3.701 11.49 2.587 ) 1"0 18 10~20 2'.994 11.34 3.040 11.36 1.352

a Each group had 15 cows ' .. " :r - t-,)

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Appendix Table 3. Grain Dry Matt

1 , . ,

Week 'GrouE H Number . Average DMI Std dev.

1 7.01 1.409

2 7.08 1.452

3 8.93 2.032

4 11.09 3.305 .

5 ~1.29 3.639

6- 10.73 3.938 - .

7 Il.52 3.613

8 Il.26 3.023

9 11.46 2.808

10 Il.04 2.970

,11 10.68 3.015 -12 10'.83 3.104

13 lL69 2.618

14 il. 54 2.449

15 -11."63 2.475

16 Il.68 2.484

17 11. 78 1.983

18 11.35 1.863-

a Each group had 15 cows

~

t ()

) a (kg/day) over Weeks

GrouE M Average DMI Std dev.

7.65 0.622

7.63 0.925

7.61 0.950

8-.36 2.115

8.04 1.732

8.26 1.857 -8.39 1.922

8.01 1.812

7.99 1.622

7.97 1.363

7 .88 1.582

7.93 1.809

8.08 1.712

7.67 1.469 .-

8.20 1.848

8.09 1.'992

7.79 1.671

7.83 1.543

~-;. &rMtP't't liP&;;,.'iH!t'B,~.,,~a.:-.--.....(l.~~~~'-b"'- .... - --,;;, ----.~

/

e~

/

GrouE·L Average DMI Std dev •

7.76 0.389

7.71 0.607

7.09 .1.531

7.61 1.785 >"

7.';8 1.647

~ 7 .. 61; 1.656 ",

7.44 1.558

7.34 1.643

7.40 2.461

, 7.28 1.600

-7.06 1.977 g

6.64 1.67.1+

6.61 1. 793 .. 6.38 1.236

6.30 1.160

6.76 1.945

5.80 0.935

5.66 0.930

:r \.A)

~ e' e

", d"

, D Appendix Table 4. Total Dry Matter ,Intake (kg/day) over Weeks a

---- -~ ~ ---- - -- -~~--- ·-----F

Week Grou~ H Grou~ M Gr.ouE L

,-.fi-"" NUmber Average DM! Std dev. Average DMI l Std dey. i\.verage DM! Std dev~

, 0

1 13.47 3.589 14.75 ) 1.961 14.97 2.412 r 2 13.52 2.277 15.44 2.079 15.49 2.603 J 3 16.15 2.872 16.22 ~ -3.135 o .., 17 .94 3.592

4 19.59 4.570 19.06 3.778 18.19 3.081

5 "l] 19.65 3.779 17.80 2.796 18.46 3.636 •

6 20.46 3.449 17.70 3.766 Î8.04 2.982 > 1-

7 20.90 3.274 18.57 2.467 18.77 3.365 "-

,8 21.40 2.315 18.71 2.710 18.82 3.857

9 21.35 2.159 i9.52 2.467 20.23 3.299 .~

10 21.06 2.283 18.51 2.765 19.56 3.458

11 19.99 3.112 19.48 2.441 . 19.36 3.085 #

-~ < '

20.07 3.113 19.80 r 3.312 18.80 3.549 Q

22.05 3.379 19.48 2.588 ... 18.91 2.419 /

14 22.35 3.018 19.64 3.548 18.01 2.344

15 22.34 3.530 19.44 3.276 18.89 2.910

16 22.8.0 3.322 19.63 4.031 18.37 2.650

17 22.45 • 3. 43Q.- 20.61 4.082 17.28 3.056

18 21.55 2.945 19.11 3.854 17.02 1.919

a =r Each group had 15 cows ,c-

I

·tt

Appendix Table 5. Body Weight (BW) over Weeks

r

a

.' ~ .. ./ f~.~ ;J_~.r,?~ ·-:~'::'..,~(~~j;à;f~_ -~J-~!(:~~~;"r.:.~~ -n ,~fdj:f;~;.-ri.~~i:-:;

e

Week GrouE R GrouE M GrouE L Number Average BW (kg) Std Dev. Average BW (kg) Std Dev. Average BW (kg) Std Dev.

1 597.73 65.66~ 598.46 63.554 615.09 51.904 "\

2 580.89 64.998 582.28 62.556 601.12 51. 802

563.11 ~

3 61. 921 573.33 60.981 586.97 47.459

4 556.43 60.973 568.95 . 60.006 582.83 45.314

5 554.71 59.293 565.65 63.147 571.49 42.691 -

6 552.77 57.042 565.74 56.544 568.19 36.247 c f

7 557.91 55.293 560.21 59.005 563.39 38.799 1 j ,

8 562.39 52.166 561.87 62.443 564.81 42.819 "'" 9 566.29 SL816 568.71 56.536 567.83 40.9.04

-

'10 570.31 49.113 565.35 52.541 566.92 37.848

11 573.51 52.858 570.46 54.376 569.77 39.828

12 569.10 48.876 571.46 56.989 566.80 38.539

13 578.05 48.465 577.29 53.297 564.32 40.00B

14 .581. 50 48.545 574.87 58.503- 566.14 390146

15 579.98 50.039 570.61 61.666 568.53 34.955

16 585.85 49.399 ,-/

574.97 61.382 564.45- 40.613

17 591.26 48.527 578.81 62.603 560.33 38.678

18 584.88 51.007 586.36 62.154 562.00 46.540

a Each group had 15 cows ...

o 7" Ut

" ••••••••••• lIiirrr.1lii7111il17I1rBirl~IIIii·Ii'5Iii~ÎliI",iIl".."".m!iJ~fjf;~ .... <:Io~«lft"'·l·ZW zr u·,~."c ... '>.,,,,.·.,.t ',_~Ion'io..~~..r.r;>;!~ J,~,--~..-. ....... ___ ",

( ,

t ."

~'j)

!::::

o

o e ./

Appendix Table 6. Fat Corrected Mi1k (kg) over Weeks a

t

, Week GrouE H GrouE M GrouE L Number / Average FCM Std Dev. Average FCM Std Dev. Average FCM Std Dev.

,1 22.75 10.309 21.40 7.943 23.73 9.526 i 2 29.04 7.569 29.13 7.941 31.82 9.549 3 30.13 7.966 28.08 5.295 32.19 8.839

4 29.77 6.727 .. 29.57 6.103 32.09 9.089 5 30.30 5.519 29.30 6.409 31.71 8.136

6 28.40 5.761 28.39 5.586 31.81 6.267 7 2'.52 6.238 27.78 5.262 30.67 7.283

8 31.59 8.616 27.22 4.928 29.-94 . 6.580

- 9 29.39 5.157 26.76 5.376 29.59 5.998 10 28.00 4.424 26.98 6.262 29.90 6.264 il 27.'91 4.085 26.81 6.128 27.99 8.476 ..-

12 26.91 4.343 25.86 5.531 27.27 5.617 13 27.31 -,4.915 26.58 6.452 26.71 4.920 14 26.55 4.975 26.08 6.793 26.65 5.269 15 2'6.40 4.933 25.41 6.133 24.63 5.686 16 25.15 4.628 -

" 25.43 5.957 24.23 5.088

17 26.29 4.447 26.10 6.735 23.87 5.707 18 25.79 5.193 24.93 7.269 24.53 4.866

a Il Each group bad 15 cows

~ :r 01

" -d

I!'

/ "

!.

Appendix Table 7. Ana1ysis of Variance: Effect of Groups and Parity on the Wet Hay1age Intake.

Source d. f. SS MS F

Group 2 266.94 133.47 12.51** \

Psrity 1 96.24 96.26 9.02**

Residua.1 41 437.51 10.67 1.00 1

** Significant (F<O.Ol).

Appendix Table 8. Analysis of Variance: Effect of Groups and Parity on the Dry Hay1age lntake. c'

Source d. f. ' Ss MS F

Group 2 19.05'" 9.52 2.84t

Parity 1 12.56 12.56 3.75t

Residual 41 137.38 3.35 1.00

t On1y' significant, st P<O.10

, , ., 't

A-7

l'

l't} :

" 4" '"

~:,./

Appendix Table 9. Analysis of Variance: Effect of Groups and Parity on the Hay1age NE Intake.

Source d.f. SS MS F

Group 2 16.16 ' 8.08 0.91n8

Parity l 17.67 17.67 2.00ns

Residual 41 363.08 8.85 1.00 (

,)

1 ns Non s1gnif1cant

}

Appendix Table 10. Ana1ysie of Variance: Effect of Groups and : Parity on the FCM Production.

Source d.f. SS M~ F

Groul' 2 11.11 5.56 0.49

Parity 1 536.12 536.12 47.24**

Residual 41 465.33 Il.34 1.00

'" •• Significant, (P<O.Ol). ,

li>

\ .

i \

A-8

>,

'1>-,

"

1 1 l ' 1

.. "",,:p~II!fIAIIQtUiI'. i Il l]lJjl!_UU.ililltU •••• 1 i] IlS.. a: •• JElt JIU.... !lm). t .JUIlI [jlflll &6 UlEitut lit b

A-9

Appendix Tab1e.1l. Nutrient Intake versus their,ea1cu1ated requirement.

~ Reguirement Consutn12tion Ratio ,.

Nutrient gtI' Sta- Dev. gtI' Std Dev. Cons. [reg. GROUP H

'NElaet (Meal) 29.90 4.513 30.12 6.081 1.02

". Dig. protein (kg) 1. 78 0.314 2.48 0.569 1.42

Ca (kg) 0.10 0.017 0.28 0.065 2.88

P (kg) 0.07 0.013 0.19 0.058 , 2.65

Mg (kg) 0.22 0.019 0.36 - 0.057 1.66

K (kg) 0.87 O. 074 1.82 0.194 2.09

Ca/p ratio 1.35 0.001 1.54 0.402 1.14

KI (Ca+Mg) ratio 2.75 0.187 1.03 0.111 0.38

GROUP M

Nel~et (Meal) 29.23 4.590 26.79 ~.277 0.93

Dig. protein (kg) 1. 73 0.319 2.30 0.609 1.36

Ca (kg) • 0.10 O. 017 0.26 0.065 2.72

P (kg) 0.07 O. 013 0.15' 9. 036 2.18

Mg (kg) 0,.22 0.017 ,0 .. 34 0.046 1.56

K (kg) 0.89 0.068 1.92 0.204 2.18

Ca/P ratio 1. 35 0.001' 1.72 0.415 1. 27

K/Ca+Mg) ratio 2.79 0.196 1.12 0.125 0.40

GROUP L

Ne • laet

(Meal) 30.04 5.396 25.18 ~. 26~ 0.85

Dig. protein (kg) 1.80 0.374 2.16 0.46q 1.24

Ca ,(kg) 0.10 ,0.020 0.25 0.047 2.55

P (kg) 0.07 0.015 Q.15 0.034 2.02 1 1

Mg ~kg) 0.21 0.016 0.35 0.040 ' ,1.,64 j

! \ ,

K (~) , 0.85 0.063 \ 2.01 0.186 2.36 ;

• j Ca/P.ra~io 1.35 0.001 1. 76 0.427 1.30

1 K/Ca+Mg) ratio 2,.73 0.206 1.17 0.144 0.43 ~

,< ct 1 ',;:

l'<"~ ... "

\t ':~ h

~\~ a~' h~ ~~

"~F, .. ' ,..~ ,

,

·~~-: ~, ""Y"

St $ la _______ -_....wcue>A ;;=SC" ;:m:;;4Q_

<:: o • " l') a Appendix Table 12. Total NE1 Ca1cu1ated Requirement (Mca1/day) over Weeks

.1;11 , act

"1 , .' ;.il ~ Week GrouE H GrouE M GrouE L

NÙmber Average NE Std dev. Average NE Std dev. Average NE Std dev •.

1 26.44 7.513 25.56 5.805 27.15 7.272 -- , 2 30.89 5.683 t 31-.09 5.911 32.97 7.120

3 31.47 6.066 30.20 3.918 33.08 6.424 '

4 31.13 5.109 31.25 4.563 32.92 6.592

5 31.49 4.159 31.01 4.589 32.55 5.868

6 30.07 4.294 30.34 4.056 32.58 4.554

7 30.96 4.386 29.81 ,3.769 31.68 5.422

8· 32.55 6.327 29.4.2 3.532 31.16 4.733

9 30.97 3.579 29.17 4.060 ,

30.94 4.287

10 30 .. 00 3.245 29.28 4.473 31.16 4.278

11 29.97 2.711 29.23 4.268 29.79 5.898 12 - 29.18 2.899 ( 28.54 3.916 29.22 3.7,98

13 29.58 3.379 29.15 4.583 28.77 3.202 , 14 29.06 3.376 28.75- 4.909 28.75 3.563

15 28.93 3.259 28.20 4.281 27.29 3.830

16 28.07 3.168 28.26 4.369 26.94 3.496 /

17 28.98 4!876 2.995 28.81 26.,63 3.932

18 28.52 3.660 28.04 5.120. 27.14 3.419

a Each group had 15 cows

/

If.

/

>. .... o

- "

,~

f' , 1

t~

1 ~ ~ :>: :(':',

, ,

LI " 1

o .,

1 Appendix "'fable 13. Total NE1act Consumption (Mcal/day) over Weeksa

1i

GrouE H GrouE M Number Averase NE Std dev. 'Averase NE 'Std dev.

1 20.44 4.841 21.99 2.826

2 20.40 2.976 22.60 2.~80

3 24.68 4.261 23.61 4.359 -

4 29.86 6.893 27.44 5.409

5 30.22 5.446 25.68 4.291

6 31.11 s-:-598 26.09 5.534

7 31.72 4.-793 /27.05 4.094

8 32.39 3.189 27.49 4.533

9 32.26 3.603 28.43 4.657

10 31.52 3.379 27.20 4.946

11 30.18 5.062 28.40 4.449

12 30.39 4.853 28.70 6.005

13 33.01 5.094 28.04 4.711

14 33 ___ 38 5.095 28.22 6.107

15 33.02 5.362 - 27.79 5.426

16 33.38 4.698 27.99 6.527

17 32.78 4.710 28.96 6.404

18 31.38 4.48R 26.57 5.793

-. a Each group had 15 cows

"f,.' ~~

nf,I

GrOUE L Avera.ge NE .

22.58

22.78

24.83

26.12

26.40

25.71

26.65 ,

26.06

28.13

26.50-

26.34 25.25

25.47

24.30

25.59

25.01

23.21

22.38

Std dev.

2.743

2.696-

" 4.,676

4.059

4.675

3.274

4.595 -5.212

5.182

5.322

4.147 4.827

3.~45

3.516

4.032

3.802

4.525

2.520

•

f

..

> 1 ..... .....

.,

--, _."-,,1