How Do I Decide What Traits are Important? Carcass/Ultrasound EPDs

1. How Do I Decide What Traits are Important? Carcass/Ultrasound EPDs Bob Weaber GRA-Cornell Univ. Animal Breeding Group rlw26@cornell.edu

2. Overview • Which trait should be used in making selection decisions? • Ultrasound or Carcass • The value of ultrasound records • Overview of various breed carcass/ultrasound genetic evaluations Brown Bagger – Beef Cattle Genetics: Fine Tuning Selection Decisions

3. Alternate Production Circumstance • Feedlot owner buying bulls for the production of forward contract weanling cattle Brown Bagger – Beef Cattle Genetics: Fine Tuning Selection Decisions

4. Example Feedlot Goal • Maximize the income from beef (carcass) less the production costs • Production costs include weanling purchase price and per diem feeding costs Brown Bagger – Beef Cattle Genetics: Fine Tuning Selection Decisions

5. Example List of Traits • Carcass attributes (eg carcass marbling) • Ultrasound attributes (eg ultrasound marbling) • Days to finish Brown Bagger – Beef Cattle Genetics: Fine Tuning Selection Decisions

6. Example Relative Emphasis • What is the increase in carcass value from a unit change in marbling score, all other traits (in the list) held constant ? • What is the increase in carcass value from a unit change in ultrasound score, all other traits (such as carcass marbling) held constant ? • What is the increase in costs from an extra day on feed ? Brown Bagger – Beef Cattle Genetics: Fine Tuning Selection Decisions

7. The Answer • Ultrasound attributes have no value in themselves when the income is determined by the corresponding carcass attribute and the ultrasound phenotypic measures have been used in the multiple trait assessment of carcass attributes Brown Bagger – Beef Cattle Genetics: Fine Tuning Selection Decisions

8. The value of ultrasound records Brown Bagger – Beef Cattle Genetics: Fine Tuning Selection Decisions

9. Genetic Correlations • Carcass traits • Economically relevant • Observed in fed steer and heifer carcasses • Ultrasound • Indicator • Observed on yearling breeding stock • Genetic correlation links them • Want genetic predictors for carcass trait • Have (most) phenotypes on indicator trait Brown Bagger – Beef Cattle Genetics: Fine Tuning Selection Decisions

10. Genetic correlations SE (h2) < 0.07, SE (Rg) < 0.13 Crews et al. 2003a Brown Bagger – Beef Cattle Genetics: Fine Tuning Selection Decisions

11. Why should we use ultrasound data? • Strong, positive genetic correlations • Suggests a high proportion of the same genes affect both traits • High heritabilities • Opportunity for rapid genetic change • Phenotypic record collection cost • Carcass ~ $100 vs. Ultrasound ~ $15 • New records (2003): • Angus: 4,290 carcass, 88,167 ultrasound • Simmental: 724 carcass, 4,426 ultrasound Brown Bagger – Beef Cattle Genetics: Fine Tuning Selection Decisions

12. Observed Carcass Data Carcass EPD Observed Ultrasound Data Ultrasound EPD Relationships Progeny Carcass Attributes True Carcass Attribute Enns, 2003 Brown Bagger – Beef Cattle Genetics: Fine Tuning Selection Decisions

13. Options • EPD calculated using carcass data • EPD calculated using ultrasound data • Carcass EPD calculated using carcass and ultrasound data • Ultrasound data is useful • Indicator trait Brown Bagger – Beef Cattle Genetics: Fine Tuning Selection Decisions

14. Does it work? • Devitt and Wilton (2001) suggested the use of yearling bull ultrasound measures for genetic improvement of steer progeny carcass traits. • Selection of high- and low-line IMF phenotype sires randomly mated resulted in significant differences in progeny USDA QG. (Sapp et al. 2002) • Inclusion of ultrasound data in multiple trait evaluation improves accuracy of carcass EPD, especially for replacements with only an ultrasound observation. (Crews and Kemp, 2002; Crews et al., 2003b) Brown Bagger – Beef Cattle Genetics: Fine Tuning Selection Decisions

15. Current Carcass/Ultrasound Genetic Evaluations Brown Bagger – Beef Cattle Genetics: Fine Tuning Selection Decisions

16. Current Genetic Evaluations *Working to incorporate carcass data, Spring 2004 release Brown Bagger – Beef Cattle Genetics: Fine Tuning Selection Decisions

17. Current Genetic Evaluations *Multi-breed model Brown Bagger – Beef Cattle Genetics: Fine Tuning Selection Decisions

18. Which EPDs do I use? • Angus • Older animals- • Compare accuracy values from each evaluation • If very different use EPDs with highest accuracy • If similar use Carcass EPD given similar percentile rank as Ultrasound EPD • Else, use Ultrasound EPD • Young animals with own ultrasound observation or those with low carcass EPD accuracies • Ultrasound EPDs • Other breeds • Use reported EPDs Brown Bagger – Beef Cattle Genetics: Fine Tuning Selection Decisions

19. Selected References • Crews, D. H., Jr. and R. A. Kemp. 2002. Genetic evaluation of carcass yield using ultrasound measures on young replacement beef cattle. J. Anim. Sci. 80:1809-1818. • Crews, D. H., Jr., E. J. Pollak, R. L. Weaber, R. L. Quaas, and R. J. Lipsey. 2003. Genetic parameters for carcass traits and their live animal indicators in Simmental cattle. J. Anim. Sci. 81:1427-1433. 242 • Crews, D. H., Jr., E. J. Pollak, R. L. Quaas. 2003. Evaluation of Simmental carcass EPD estimated using live and carcass data. Submitted J. Anim. Sci. • Devitt, C. J. B, and J. W. Wilton. 2001. Genetic correlation estimates between ultrasound measurements on yearling bulls and carcass measurements on finished steers. J. Anim. Sci. 79:2790-2797. • Sapp, R. L., J.K. Bertrand, T. D. Pringle, and D. E. Wilson. 2002. Effects of selection for ultrasound intramuscular fat percentage in Angus bulls on carcass traits of progeny. J. Anim. Sci. 80:2017-2022. • Wilson, D. E. 1992. Application of ultrasound for genetic improvement. J. Anim. Sci. 70:973-983. Brown Bagger – Beef Cattle Genetics: Fine Tuning Selection Decisions