From Pasture Management Guide. Time increasing GrowthDry weight accumulation Harvest Growth follows...

From Pasture Management Guide

Time increasing

Gro

wth

Dry

wei

ght a

ccum

ulat

ion

Harvest

Growth follows a sigmoid curve

Detergent Procedure to Partition Forages

Forage

Digest with acid detergent

Hemicellulose Cellulose and Lignin(ADF)

Digest with 72% sulfuric acid

Cellulose Lignin ADL

Digest with neutral detergent

Cell Contentsproteinsstarchsugarsorganic acidspectin

Hemicellulose, Cellulose, Lignin(NDF)

insoluble

insoluble

insoluble

soluble

soluble

soluble

Fig. 16.7. Digestibility ranges of major forage types. Dashed lines illustrate forage digestibility levels needed to meet energy requirements of different classes of beef cattle (Riewe, 1981 and Reid et al., 1988). From Forages Vol. I, An Introduction to Grassland Agriculture, 6th ed.

Fig. 16.8. Maturity effects on alfalfa quality. From Forages Vol. I, An Introduction to Grassland Agriculture, 6th ed.

Stage of Maturation:

Fig. 16.6. Forage quality analysis of leaf and stem tissue from alfalfa and timothy growing together in a mixture (Collins, 1988). From Forages Vol. I, An Introduction to Grassland Agriculture, 6th ed.

Leaves vs Stems

Forages Vol. I, An Introduction to Grassland Agriculture, 6th ed.

When K increases, winter survival increases.When N increases, winter survival decreases.


Introduction to Forages

V.G. Allen, C. Batello, E.J. Berretta, J. Hodgson, M. Kothmann, X. Li, J. McIvor, J. Milne, C. Morris, A. Peeters, M. Sanderson. 2011. An international terminology for grazing lands and grazing animals. Grass and Forage Sci. 66: 2-28 DOI: 10.1111/j.1365-2494.2010.00780.

• Pasturelandland devoted to the production of indigenous or introduced forage for harvest primarily grazing. Pastureland generally must be managed to arrest successional processes.

• Rangelandland on which the indigenous vegetation is predominately grasses, grass-like plants, forbs, or shrubs and is managed as a natural ecosystem. Often a semi-arid region. If plants are introduced, they are managed as indigenous species.

What is “forage”?

Forage - edible parts of plants, other than separated grain, generally above ground, that can provide feed for grazing animals, or can be harvested for feeding.

• Woody• Herbaceous, “herbage” non-woody

• Grass - Poaceae family

• Grass-like - vegetation is similar to grass in appearance; member of the Cyperaceae (sedges) and Juncaceae (rushes) families

• Forb - any herbaceous broadleaf plant that is not a grass or is not grass-like

• Legume - member of the Fabaceae family• Non-legume



• Pasture, animal harvest, grazing, harvested plant material is 80% moisture

• Hayfield, mechanical harvest, storage• Silage/haylage - wet; wilted; chopped;

fermented, 60 - 40% moisture• Hay - dry; wilted; baled, <20% moisture,• Pellets - dehydrated; quickly dried at 300-

1000 C; ground; pellet or cube


• Diverse plant material within a field; diverse species: grasses, legumes, forbs; diverse canopy heights; diverse rooting depths; diverse maturations, i.e. mimicing the prairie

• Few plant species; a grass and a legume species; diverse plant structure; not diverse maturation

• Monoculture; one species, often alfalfa

Annual: one year, harvested immature, typically harvested for grain, for ex. small grain haylage/silage, corn silage, sorghum silage, sorghum-sudangrass silage

Biennials: Brassica spp, (turnips) grazed the first year while vegetative

Perennials: multiple year life span



What does the consumer (animal) want?• Maximum quantity, dry matter/feeding• Maximum quality, nutritive value

The goal of the producer:• Maximum quantity (yield), dry matter/A• Maximum quality, nutritive value• Stand persistence, perennial stand

remains healthy over years

From Pasture Management Guide

Seasonal growth patterns in forages

Growth/Yield is a result of photosynthesis• Photosynthesis, capturing sunlight which used as

the energy to fix CO2, produce sugar, that is used for growth, production of dry matter, yield

• Green tissue captures sunlight, both leaves and stems

• Capturing sunlight so that no sunlight reaches the soil surface, inhibiting low growing forages in a mix, forage stand not reaching its potential

Time increasing

Gro

wth

Dry

wei

ght a

ccum

ulat

ion

Harvest

Growth follows a sigmoid curve

Sugar production leads to dry matter accumulation

cell contents

Sugar fructan or starch HemicelluloseCelluloseLignin

cell wall

growth, excess is storedstructure

Defoliation – removal of foliation (harvest) (leaves, stems)

Due to: Mechanical harvest Grazing Other organisms, animals, diseases Fire Chemicals, herbicides Extreme cold temperatures, winter

After defoliation:• For one to two weeks, above ground

growth has priority • Root growth stops, fine roots and root

hairs may die• Nutrient uptake declines• N-fixation is greatly reduced or ceases

Time increasing

Gro

wth

Dry

wei

ght a

ccum

ulat

ion

Harvest regrowth

Regrowth follows a sigmoid curve

Defoliation

The ability to fully recover will depend upon:

Availability and type of meristematic tissue

Remaining leaf area Carbohydrate reserves, nutrient levels Frequency of defoliation Environmental conditions

Remaining leaf area (LA)• LA location of sugar production, the amount of

sugar produced is proportional to the leaf area, sugar is needed for growth

• Height of cutting or bite, the more LA the faster the recovery, less the “yield”

• For growth the plant uses CHO reserves: base of the stem, crown, rhizomes, roots

• Initial spring growth, no LA, CHO reserves only• The level of N in reserves influences initiation of

regrowth, amino acids are used

Frequency of defoliation• As frequency of defoliation increases, the time

between harvest decreases• Less regrowth has accumulated, lower yields• The ability for CHO reserves to completely

replenish decreases• Resulting in less yield, slower regrowth,

weakened plants, dead plants

Figure 2. Changes that occur in dry-matter yields and CHO reserves during growth periods of an alfalfa crop.

Harvest frequency (weeks)

Yield

(ton/acre)

3 7.9

4 8.4

5 9.2

6 10.3

8 10.2

12 10.4

Effect of harvest frequency on yield.

Time increasing

Gro

wth

Dry

wei

ght a

ccum

ulat

ion

Harvest regrowth

Regrowth follows a sigmoid curve

2.5 weeks, May-June

5+ weeks, Aug-Sept

In IA:


The goal of the producer:• Maximum quantity (yield), dry matter/A• Maximum quality, nutritive value• Stand persistence, perennial stand

remains healthy over years

Amount of nutrients and the ability to get to the nutrients (digestibility of the plant material)

Structural sugars

cell contents

Sugar fructan or starch HemicelluloseCelluloseLignin

cell wall

Detergent Procedure to Partition Forages

Forage

Digest with acid detergent

Hemicellulose Cellulose and Lignin(ADF)

Digest with 72% sulfuric acid

Cellulose Lignin ADL

Digest with neutral detergent

Cell Contentsproteinsstarchsugarsorganic acidspectin

Hemicellulose, Cellulose, Lignin(NDF)

insoluble

insoluble

insoluble

soluble

soluble

soluble

Digestibility• Measured using bioassays

• In situ, or in vivo in the animal, using fistulated animals; digestion trials, apparent dry matter digestibility, (DM intake - DM out)/ DM intake

• In vitro, in test tube with rumen fluid, outside the animal, IVDMD (in vitro dry matter disappearance)

• Calculated• Total digestible nutrients (TDN), summation of the

digestibility of the different components• DDM (digestible dry matter), DDM% = 88.9 - (0.779 x

ADF%)

Forage quality needs depend upon:

• Animal species• Purpose or function of the the animal

• Lactation; greatest nutrient need• Growth, meat; younger animals > older

• Stage of development• Growing, 1-1.5 maintenance• Lactating, 2-2.5x maintenance• Maintaining

Fig. 16.7. Digestibility ranges of major forage types. Dashed lines illustrate forage digestibility levels needed to meet energy requirements of different classes of beef cattle (Riewe, 1981 and Reid et al., 1988). From Forages Vol. I, An Introduction to Grassland Agriculture, 6th ed.

Plant Species• Protein:

• legumes > cool season grasses > warm season grasses

• N fertilization can increase CP in grasses.• Fiber:

• warm season grasses > cool season grasses > legumes

• Minerals: legumes > grasses• Varietal differences: not much selection is based on

quality; more on yield, stand persistence, pest resistance

Fig. 16.8. Maturity effects on alfalfa quality. From Forages Vol. I, An Introduction to Grassland Agriculture, 6th ed.

Stage of Maturation:

Stage of Maturation• Change in maturity:

• the rate of change is species dependent, digestibility of grasses declines faster than the digestibility of legumes

• quality of stems declines with age, quality of leaves remain fairly constant

Fig. 16.6. Forage quality analysis of leaf and stem tissue from alfalfa and timothy growing together in a mixture (Collins, 1988). From Forages Vol. I, An Introduction to Grassland Agriculture, 6th ed.

Leaves vs Stems

Leaf:stem ratio• Amount of DM from the leaf portion of the forage

compared to the amount of DM from the stem portion

• Leaves have higher quality, 2x more CP in leaves in than stems, less structural CHO (fiber) in leaves than stems

• Ratio is dynamic, changes over time; stem leaf• Harvest, store, and feed LEAVES

What is the cost of poor quality forage?

NDF is a measure of quality. As percent fiber increases, intake decreases, leading to a decrease in animal production.

Adapted from data by Mertens, 1985; Pioneer Forage Manual

http://www.uwex.edu/ces/forage/pubs/auction.htm

As the forage quality increases, the price paid increases. High quality forage has a higher value.

Milk

pro

du

ctio

n (

lb/a

cre)

Milk productionIncrease = $400 profit

Milk production increases, profits increase with higher quality hay.

• Daily gain (lb of gain per day) decreases with decreasing forage quality.

• Forage quality decreases with plant maturation.

• Concentrate:forage ratio increases with forage age, resulting in increase costs.

Can I determine forage quality by just looking at it?

In the field before harvest?

In storage?

Can I determine forage quality by just looking at it?

In the field before harvest?• Stage of maturity• Leafiness vs. steminess

In storage?• Stage of maturity at harvest• Leafiness vs. steminess• Green color• Odors, molds, dust• Foreign material, weeds


The goal of the producer:• Maximum quantity (yield), dry matter/A• Maximum quality, nutritive value• Stand persistence, perennial stand remains

healthy over years

Persistence, defined as the ability of perennial plants to remain alive and productive over a long periods of time.

• Hardiness and winter survival• Disease• Management

Winter hardiness (cold resistance, winter dormancy)Metabolic changes: Begins with cooler temperatures and short daylengths Growth slows, no new plant material Photosynthesis still takes place, sugar is not used for

growth but placed in the CHO reserves, roots for legumes, stem bases for grasses

Increase in sugar storage in crown region, stem bases, or root, decreases the freezing point of the cell sap, used for regrowth in the spring

• Decrease in free water, decreases the potential for ice formation within the cell and between cells

• Species dependent• Grasses > winter hardiness compared to

legumes• Perennial ryegrass, tall fescue < winter

hardiness• Varietal differences

• Breeding programs• Annual alfalfa• Stand persistence

• Plant differences• Actively growing plants > susceptibility to winter

damage; new growth is damaged if the temperature drops below 24-25 F.

• Why? Water content is greater and sugar used for growth as opposed to storage

• Plant parts differ in their susceptibility to winter damage• Leaves > than roots > than crown region• Related to the level of water in the plant parts

Management for persistence:• Enhance soil cover

• No harvest after frost• Grasses catch more snow than legumes, mixture

• Reduce free water in the plant• Do not irrigate in the fall

• Reduce the potential of actively growing plants• Do not harvest 4-5 wks before 1st killing frost

• Fertility• Do not apply N prior to killing frost• P and K enhance winter survival

When is the ideal time to harvest:• Quantity • Persistence • Quality

Ideal time to harvest:• Quantity, at seed formation• Persistence, at maximum levels of

stored CHO• Quality, a young, vegetative stage

Ideal time to harvest:• Compromise between quantity, stand

persistence, and quality.

Compromise between quantity, stand persistence, and quality

Products• Silage/haylage - wet; 60 - 40% moisture• Hay - dry; <20% moisture• Pellets - dehydrated; quickly dried at 300-

1000C; ground; pelleted or cubed

Field/harvest losses• Physical

• DM loss; leaf loss or leaf shattering; handling forage particularly when less moist

Less drying time, wetter product (haylage), less leaf loss• Table 21 from Silage and Hay Preservation. NRAES, Bulletin 5. Handout

• Physiological• Respiration; sugars become heat and CO2; slows and becomes inhibited

at moisture content < 20%

Faster drying rate, less respiration loss• Leaching nutrients because of rain

Faster drying rate, less time in the field, less chance of getting rained on

Comparison of forage quality of standing alfalfa forage just prior to harvest with the quality of hay produced without rain damage or hay exposed to rain damage. Yield is in tons DM/acre. (Collins 1990)

2.01.7

1.5

Drying

• grasses dry faster than legumes• mature crop dries faster• heavier yields dry slower• waxy surface on leaves and stems• leaves dry at a faster rate than stems• stem thickness, 1st cut thicker than 2nd

cut

Cutting: Cutting: at appropriate stage of maturity, at a

height of 2-4 inches

Mechanical conditioning: involves crushing or crimping the stems, in order to increase their drying time, especially legumes

Chemical conditioning: Potassium or sodium carbonate, sprayed on at the time of mowing

Swath manipulation, tedding, tines rotate to stir, spread, and fluff the swath; can spread out the swath after conditioning, decreasing drying time

Raking, moves the wetter hay from the bottom to the top

Baling:• Conventional rectangular bales, 50-135 lb,

most commonly used package for cash hay, safe baling moisture% is 20%

• Big round bales, 500-2000 lb, less labor, feed on the farm, safe baling moisture% is 18%

• Large rectangular, 900-2000 lb, safe baling moisture% is 12-16%

Hay preservatives: propionic acid, allow hay to be baled at higher moisture contents, reduces the curing time by one day

Storage loss• Mold growth, at 20-35% moisture

• Molds consume nutrients, release CO2, water, and heat

• Heat may lead to fires• Molds produce toxins, spores that cause

lung damage• Reduces the value of the hay for sale

• Browning reactions, caramelization, nonenzymic browning, Maillard reaction• Results from release of heat, due to

respiration• Proteins and amino acids combine with

sugars to form a brown polymer, resembling lignin, reduced digestibility

• Releases heat causing more browning, hay fires

Weathering • Weathering: leaching of nutrients,

outside layer has greatest weathering• % hay loss decreases with increased

bale size

Silage/Haylage

Silage/haylage - wet; mowed, wilted, chopped, stored, fermented

Advantages of silage/haylage• Less time in the field, curing

• Preserves more nutrients than hay• Reduces weather risks• Reduces field losses

• Less respiration• Less rain damage• Less mechanical manipulation, less

shattering• Mechanized harvesting and feeding systems

Disadvantage of silage/haylage

• High equipment costs• Contains less vitamin D than hay• Potential for more storage loss• Loss of nutrients through the effluent

Making silage/haylage• I. Aerobic phase, respirationC6H12O6 + 6O2 6CO2 + 6H2O + heat

Length of phase is dependent of the O2

concentrationReduction in sugar (nutrients), decrease in net

energy, increase in % fiberIncrease in temperature, ideal is 70-90 F, if too

high then fire and Maillard process

Goal is to decrease O2 concentration as quickly as possible

Making silage/haylage

• I. Aerobic phase, respirationGoal is to decrease O2 concentration as quickly as

possible• Compaction of the forage

• Proper cut length, 1/2-1 inch for direct cut silage; 1/4 to 1/2 inch for wilted; 3/8 inch for forage; 1/4 inch for corn

• Sealing the silo, keeping O2 out

• II. Lag phase

• III. Fermentation phase, anaerobic

The bacteria converts carbohydrates to a small amount of acetic acid first, then lactic acid

glucose (6C) 2 lactic acid (2, 3C) + heat

4% loss of energy in the form of heat

High lactic acid levels causes the pH to drop, ideal would be 70% of the acid present was lactic acid. Lactobacillus bacteria

14 days for good fermentation

• IV. Storage for a long time

When fermentation process goes bad . . .• Clostridia, predominate bacteria, spores in

manure and the soil• Clostridia converts lactic acid to butyric acid

(4C) and 2CO2

• Substantial energy loss, 23% (butyric) vs 4% (lactic)

• Rancid odor, reduced palatability, high level of ammonia-N, greater than 10% of total N, pH higher than 5.0

• Too little carbohydrates (low sugar content), moisture content too high, high pH (above 5.0), aerobic condition, low numbers of Lactobacillus

Silage additives• Acids to decrease pH, commonly used in Europe: Formic

acid; propionic acid, usually not cost effective• Microbial inoculates, increase the number of

Lactobacillus bacteria, results are variable, successful if increasing the bacteria numbers by at least 10%

• Carbohydrates, grain, molasses• Increase fermentable CHO

• Nonprotein N• Increases CP

• Enzymes, hemicellulase, cellulase• Breakdown of structural CHO, more fermentable CHO• Varying degrees of success

Added labor and costs, better to harvest at appropriate stage

Purchased products are not substitutes for good management

Garbage in garbage out

Oxygen

FeedingPhase

Unloading

• Keep silage covered• Remove only what is needed• Little surface face area • Smooth surface area

When K increases, winter survival increases.When N increases, winter survival decreases.


Comparison of forage quality of standing alfalfa forage just prior to harvest with the quality of hay produced without rain damage or hay exposed to rain damage. Yield is in tons DM/acre. (Collins 1990)

2.01.7

1.5

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