Improvement of Beef Cow Biological Efficiency

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

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 EfficiencyFeed:Gain < 2:1 < 3.5:1 > 6:1

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

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

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 Low milk production Low visceral organ weight Low body lean mass High body fat mass Low output and low input • High milk production • High visceral organ weight • High body lean mass • Low body fat mass • High output and high input

13. Environment Restricted feed resources Abundant feed resources 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 • 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 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 • 2 week intake evaluation • BW, body condition score, ultrasound fat • Repeat again as 5-year-old mature cows

15. Variation in cow efficiency Adcock et al., 2011

16. Correlations of heifer and 2 year-old cow traits Correlations in bold are significant at P ≤ 0.05

17. Ongoing project • Intake on 486 heifers postweaning • Intake on 274 2-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 • 2 day initial and final weights (70 d test) • Ultrasound 12th rib fat thickness • Weighed every 2 weeks

21. Grain Diets Target 2 lbs/d gain Forage Target 4 lbs/d gain

22. Forage – Grain (spring-born) Correlations in bold are significant at P ≤ 0.05

23. Forage – Grain (fall-born) 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?