Residual Feed Intake and the Cow Herd A. M. Meyer 1 *, R. L. Kallenbach 2, M. S. Kerley 1 University...

Residual Feed Intake and the Cow

Herd

A. M. Meyer1*, R. L. Kallenbach2, M. S. Kerley1

University of Missouri, Columbia1 Division of Animal Sciences

2 Division of Plant Sciences

2007 NBCEC Brown Bagger Series

10/17/07 NBCEC Brown Bagger Series Allison Meyer

Residual Feed Intake (RFI) RFI = actual intake – expected intake

-RFI → more efficient +RFI → less efficient

By definition, phenotypically independent of growth and mature size

Moderately heritable


Previous RFI Research Comprehensive research project at the

Agricultural Research Centre at Trangie, New South Wales (1993-2000) Divergently selected for RFI Studied the impacts of RFI upon other traits

Research has also been established in US and Canada Greater availability of equipment and technology to

record individual feed intake and weights

Overall findings: Low RFI calves have lower feed intake yet similar performance to high RFI calves


RFI and the Cow Herd Feed is the greatest non-fixed cost for beef cow-

calf producers 56-59% of total operating costs for US cow-calf

producers (USDA ERS, 2005)

Despite this, little research has been done to determine the impact of selection for RFI upon cow intake, performance, and profitability RFI determination limits numbers than can be used Difficulty of measuring pasture intake Production scenarios more difficult to control Unknown effects of changing diet and environment upon

RFI and intake


Current Research

Objective:To determine the effect of residual feed intake rank on the grazed forage intake and performance of beef cows


Establishment of Research Herd

42 purebred Hereford heifers, donated by 19 producers to the University of Missouri RFI determined feeding alfalfa-grass mixed hay

with GrowSafe feed intake system

Heifers were split into: Low RFI (highly efficient) Mid RFI High RFI (lowly efficient)


Research Timeline

Summer 2005

RFI

Dete

rmin

ati

on

Fall 2005

1st C

alv

ing

Seaso

n

Winter/ Spring 2007

Fall 2006

Summer 2006

Exp

eri

ment

12

nd C

alv

ing

Seaso

nExp

eri

ment

2

Mid – late gestation

Early gestation &

Late lactation DOB: Feb 26, 2001 - Feb 20, 2004

Not all cows calved during first calving season


Experiment 1 84 d grazing trial

May 18 – Aug 9, 2006 Low RFI vs. High RFI cows Mid-late gestation

Non-endophyte infected tall-fescue based pasture Grazed continuously 4 paddocks (n = 7/rep, 1.8 - 2.4 ha)

Forage measurements Exclosures used to measure growth Rising plate meter readings and buffer areas

used to keep similar forage availability among paddocks


Cow Performance- Exp. 1

Variable Low RFI High RFI SEM P

RFI, kg/d -4.37b 5.04a 0.70 0.006

Initial BW, kg 591.2a 565.0b 1.2 0.004

Initial BCS 5.26 5.26 0.07 1.00

BW Change, kg

19.5 22.1 3.4 0.68

BCS Change 0.11 0.10 .05 0.86

a.b P < 0.01


12.415.6

0

2.5

5

7.5

10

12.5

15

17.5

DM

I, k

g/h

d/d

21%

Forage Dry Matter Intake- Exp. 1

Low RFI High RFIP = 0.23


Pasture Carrying Capacity- Exp. 1


Area grazed, ha

1.71 1.82 0.05 0.35

DM on offer, kg

4215b 4376a 11 0.06

a.b P < 0.10


Experiment 2 60 d grazing trial

Feb 23 – April 23, 2007 Low RFI vs. High RFI pairs Late lactation

Stockpiled tall fescue and new spring growth Strip-grazed 3 paddocks each (n=4 pairs, 0.73-0.93 ha) Fed 3.3 kg soyhulls/pair

Forage measurements Pre- and post-grazed areas sampled ~14 d Forage growth was estimated using a growing degree

days calculation


Cow and Calf Performance- Exp. 2


Cows

RFI-4.22b 5.13a 0.26

<0.0001

Initial BW, kg 569.4 557.2 10.5 0.46

Initial BCS 4.85 4.98 0.14 0.55

BW Change, kg

18.4 26.6 10.0 0.59

BCS Change -0.04 0.15 0.08 0.19

Calves

Age, d 144 143 7 0.87

Initial BW, kg 140.7 131.5 6.0 0.34

ADG, kg/d 0.85 0.95 0.08 0.45a.b P < 0.0001


Forage Dry Matter Intake for Cow-calf Pairs- Exp. 2

12.514.1

0

2.5

5

7.5

10

12.5

15

17.5

DM

I, k

g/h

d/d

Low RFI High RFIP = 0.12

11%


15.817.4

0

2.5

5

7.5

10

12.5

15

17.5

20

DM

I, k

g/h

d/d

Total Dry Matter Intake for Cow-calf Pairs- Exp. 2

9%

Low RFI High RFI

3.3 kg soyhulls/ pair


Dry Matter Intake Current study

Exp. 1: Low RFI cows had 21% lower grazed forage DMI

Exp. 2: Low RFI pairs had 11% lower grazed forage DMI, 9% lower total DMI

Cows in the current studies appeared to remain in their RFI group

Correlation of RFIpost-weaning and RFIcow Phenotypic : 0.36 - 0.40 Genetic: 0.98 (Arthur et al., 1999; Archer et al., 2002)


Dry Matter Intake Why difference between Exp. 1 and 2?

Calves in second study may have affected DMI difference, as they were of unknown RFI rank

Maintenance, gestation, and lactation may affect efficiency differently (Hughes and Pitchford, 2004)

Why lack of significance? Difficulty of measuring forage intake Low numbers used in current study


Dry Matter Intake Herd et al. (1998): Compared grazed forage intake

of low and high RFI cows with calves using alkanes Small numerical difference in DMI

Arthur et al. (1999): Redetermination of RFI for 4 yr old open, non-lactating cows on pelleted, hay-based ration 4.5% decrease in DMI for low vs. high RFI cows (P < 0.05)

Growing cattle on concentrate diet RFI determined: Low RFI steers have 12-17% lower DMI

(Nkrumah et al., 2003; Kolath et al., 2006; Nkrumah et al., 2006; Castro Bulle et al., 2007)

Divergently selected: Low RFI steers have 6-11% lower DMI (Richardson et al., 1998; Arthur et al., 2001)


Mature Size

Current Study: Cows were managed together pre-trials Exp. 1: Low RFI cows were heavier (P < 0.05) Exp. 2: No differences

Low RFI cows may have increased BW Significantly heavier (Herd et al., 1998)

Numerically heavier at all time points during 4-yr study (Arthur et al., 2005)

No difference (Arthur et al., 1999)

Genetic correlation between RFIpostweaning and BWmature

-0.09 ± 0.26 (Herd and Bishop, 2000)

-0.22 (Archer et al., 2002)


Performance Growth and body weight change

Current study: No difference in Exp. 1 or 2 Typical of results in cows (Arthur et al., 1999; Arthur et al., 2005)

and growing steers (Arthur et al., 2001a; Basarab et al., 2003; Kolath et al., 2006; Castro Bulle et al., 2007)

Pre-weaning calf gain Current Study: No difference No difference in ADG or weaning weight (Arthur et al., 2005)

Milk production No difference (Arthur et al., 1999; Arthur et al., 2005)

Low RFI cows maintained 15% greater calf BW/cow DMI (P = 0.07) (Herd et al., 1998)


Body composition Current study:

Exp. 1: No differences Exp. 2: High RFI cows had numerically higher initial BCS

and positive BCS change Mature cows

No differences in rib/rump fat depth (Herd et al., 1998; Arthur et al., 1999)

High RFI cows had greater rib fat over 4 years, no effect upon reproduction (Arthur et al., 2005)

Growing steers High RFI steers had greater back fat thickness and/or

carcass fat (Richardson et al., 1998; Richardson et al., 2001; Basarab et al., 2003; Nkrumah et al., 2004)

Genetic correlation between RFI and rib fat 0.17 (Arthur et al., 2001) - 0.33 (Nkrumah et al., in press)


Another question Reproduction

Very little data in beef cows No difference in pregnancy rate, calving rate, weaning

rate Low RFI cows had a later calving date (P < 0.10) and

greater percentage sired via natural service (Arthur et al., 2005)

Negative effect upon reproduction in litter bearing species (Pitchford, 2004)


Conclusions

Low RFI cows had numerically lower grazed forage intakes than high RFI cows

Low RFI cows may be heavier at maturity and have less fat deposition than high RFI cows

Further research is necessary to confirm these differences and investigate other production parameters

► Selection for low RFI animals may decrease feed inputs necessary in cow-calf production Greatly aided by marker for RFI status

Questions?Thank you.

Residual Feed Intake and the Cow Herd A. M. Meyer 1 *, R. L. Kallenbach 2, M. S. Kerley 1 University...

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