1. Improvement of Beef Cow Biological Efficiency
Dan Shike, PhD
University of Illinois
Champaign-Urbana

2. Why all the buzz about efficiency?
Increasing world population
Increased utilization of feed for fuel
Increasing feed cost (including forages)
Other inputs increasing in cost
Fuel, transportation, fertilizer 2

3. Profitability Traditional focus on outputs
Feed costs have historically been 50-70% of the cost of production in beef enterprises
As corn prices approached and exceeded $7 per bushel, feed costs were nearly 80% of the costs in many feedlot operations in US

4. Feed Efficiency Feed:Gain
< 2:1
< 3.5:1
> 6:1 4

5. Why are beef cattle less efficient?
Maintenance requirements
50% of total energy expended in beef production is used for maintenance of the cow
High fiber diet
Rumen fermentation
Bacteria produce VFA
Bacteria produce methane 5

6. Why haven’t we made any progress?
No selection for feed efficiency
Why?
Requires individual feeding
Expensive facilities
High labor requirement
Lack of social interaction decreases feed intake
Difficulty in defining efficient female 6

7. Measures of feed efficiency
Feed conversion ratio (FCR)
Residual feed intake (RFI)
Residual BW gain (RG)

8. Measures of efficiency
Residual Feed Intake (RFI)
The difference between actual intake and predicted intake based on animal’s gain, maintenance requirements for its body weight, and composition
NEGATIVE RFI IS GOOD!
Required less feed then predicted
Independent of growth and mature size
Linked to biologically relevant traits associated with feed efficiency
Digestibility, heat production, protein turnover

9. Measures of efficiency
Residual BW Gain (RG)
The difference between actual gain and predicted gain based on animals intake, maintenance requirements for its body weight, and composition
POSITIVE RG IS GOOD!
Gained more weight than predicted
Correlated to growth

10. Beef cow efficiency What about cow efficiency?
~70% of feed resources for cowherd
~70% of feed for maintenance
50% OF ALL FEED TO MAINTAIN COWHERD
How do we define cow efficiency?
Pounds of calf weaned per cow exposed
Pounds of calf weaned per cow exposed per unit of feed energy consumed
What about longevity?

11. Efficient Cow
Can you tell by looking at them?

12. Maintenance energy High Maintenance Cow Low Maintenance Cow
High milk production
High visceral organ weight
High body lean mass
Low body fat mass
High output and high input
Low milk production
Low visceral organ weight
Low body lean mass
High body fat mass
Low output and low input

13. Environment Restricted feed resources Abundant feed resources
Favors more moderate size, moderate milk production
“Low maintenance” breeds are most efficient
Angus, Red Poll
High maintenance breeds are least efficient
Simmental, Charolais, Limousin, Gelbvieh
Favors larger, heavier milking biological types
“High maintenance” breeds are most efficient
Simmental, Charolais, Limousin, Gelbvieh
Low maintenance breeds are least efficient
Hereford, Angus, Red Poll
Jenkins and Ferrell, 1994

14. Cow efficiency research
Funded by American Angus Association
Post-weaning intake evaluation on replacements
All females given opportunity to breed
Evaluate 2-year-old cows
60 d postpartum evaluation period
2 week intake evaluation
BW, body condition score, ultrasound fat, milk production
240 d postpartum evaluation
BW, body condition score, ultrasound fat
Repeat again as 5-year-old mature cows

15. Variation in cow efficiency
Small Cow
Big Cow
Moderate Cow
BW, lbs
1186
1453
1305
1307
Milk Production, lbs
15.9
22.9
17.9
20.5
BCS
5.5
6.0
DMI, lbs
56.7
45.4
54.5
35.7
Adcock et al., 2011

16. Correlations of heifer and 2 year-old cow traits
CowL DMI
CowL BW
CowL Milk
CowDry DMI
CowDry BW
Heifer
DMI
0.45
-0.21
-0.17
0.42
0.09
Heifer RFI
0.20
-0.01
-0.04
0.15
0.02
Heifer RG
-0.11
0.12
-0.05
0.14
CowL = Cow traits at 60 d postpartum (lactating)
CowDry = Cow traits at 240 d postpartum (dry cow)
Correlations in bold are significant at P ≤ 0.05

17. Ongoing project Intake on 486 heifers postweaning
Intake on year-old cows
Intake on 34 5-year old cows
2nd year of 5-year-old cows this year
Continue to evaluate fertility, productivity, and longevity

18. National Program for the Genetic Improvement of Feed Efficiency in Beef Cattle

19. Intake x Diet
Is there a genetics x diet interaction for intake or RFI?
Feedlot efficiency trials – high-energy, grain-based
Cowherd – moderate to low-energy, forage-based
Why would they be the same?
Maintenance energy (heat production, protein turnover)
Why might they be different?
Intake regulation
Grain – chemostatic
Forage – fill-regulated

20. Forage vs. Grain 162 spring-born, Charolais-sired calves
274 fall-born, Charolais-sired calves
Period 1 (half on forage; half on grain)
3 week transition / adaptation period
2 day initial and final weights (70 d test)
Ultrasound 12th rib fat thickness at start and finish
Weighed every 2 weeks
Period 2 evaluation (all cattle on grain)
3 week transition/adaptation period
Ultrasound 12th rib fat thickness

21. Diets Forage Grain Ingredient % of diet, DMB Husklage 47.5
Alfalfa haylage
Supplement 5
NEm = Mcal/kg
NEg = Mcal/kg
Ingredient
% of diet, DMB
High moisture corn 20
Ground corn 30
Husklage 25
DDGS 15
Supplement 10
NEm = Mcal/kg
NEg = Mcal/kg
Target 2 lbs/d gain
Target 4 lbs/d gain

22. Forage – Grain (spring-born)
Item
Forage DMI
Forage
ADG
Forage RFI
Grain DMI
Grain ADG
Grain
RFI
DMI 1
0.69
0.58
0.57
-0.09
0.26
0.00
0.51
0.01
0.13
0.21
-0.06
0.41
0.53
Correlations in bold are significant at P ≤ 0.05

23. Forage – Grain (fall-born)
Item
Forage DMI
Forage
ADG
Forage RFI
Grain DMI
Grain ADG
Grain
RFI
DMI 1
0.70
0.51
0.62
-0.29
0.15
0.00
0.40
-0.22
-0.04
0.28
0.01
0.35
0.18
0.66
Correlations in bold are significant at P ≤ 0.05

24. Summary Variation in feed intake and efficiency
Opportunity to select for and improve
Best measure / definition of efficiency?
Depends if it is feedlot or cowherd
Depends if it is for selection or research
Need to continue to collect phenotypes
Need INTAKE
Understand relationships of traits
Geneticists will determine best tools for selection

25. Questions?