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Genetic Evaluation of Carcass Data Using Age, Weight, Fat, or Marbling Endpoints

Genetic Evaluation of Carcass Data Using Age, Weight, Fat, or Marbling Endpoints. 2003 BIF Selection Decisions Committee May 29, 2003 Janice M. Rumph Montana State University – Bozeman. Carcass EPDs. Many breed associations are printing some form of carcass EPDs Based on an age constant

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Genetic Evaluation of Carcass Data Using Age, Weight, Fat, or Marbling Endpoints

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  1. Genetic Evaluation of Carcass Data Using Age, Weight, Fat, or Marbling Endpoints 2003 BIF Selection Decisions Committee May 29, 2003 Janice M. Rumph Montana State University – Bozeman

  2. Carcass EPDs • Many breed associations are printing some form of carcass EPDs • Based on an age constant • Few producers kill cattle based on an age constant • Back Fat • Carcass Weight • Marbling

  3. Are we doing things wrong? • There is nothing wrong with adjusting data to an age-constant basis… • If you are killing on an age-constant basis • If ranking of animals does not change with different endpoints ?

  4. Initial Research • Endpoints can alter expression of genetic differences (Koch et al., 1995) • Ranking of Simmental sires has been shown to be differ by slaughter endpoint (Shanks et al., 2001)

  5. Data 16,081 animals with carcass data 16,080 – Carcass Weight 15,770 – Percent Retail Cuts 12,056 – Marbling 8586 – Ribeye Area 8382 – Fat Thickness 18,133 animals in pedigree

  6. Adjustments • Age – 475 d • Had to be at least 365 d at slaughter • Carcass Weight – 750 lb • Had to be less than 1150 lb • Marbling – 500 (Small; Low Choice) • Had to be between 100 (Devoid) and 1000 (Abundant) • Fat Thickness – 0.35 in • Had to be less than 1.5 in

  7. Other Traits • Ribeye Area • Had to be greater than 6 in2 • Percent Retail Cuts • Had to be between 40 – 60%

  8. Results

  9. Estimates of Heritability Trait Adjustment

  10. Correlations – Fat Thickness

  11. 415 Age Adjusted 915 Carcass Weight Adjusted 651 Age Adjusted 186 Carcass Weight Adjusted Fat Thickness Carcass Weight Adjusted Rank r = 0.96 Age Adjusted Rank

  12. 9 Age Adjusted 1000 Marbling Adjusted 988 Age Adjusted 92 Marbling Adjusted Fat Thickness Marbling Adjusted Rank r = 0.85 Age Adjusted Rank

  13. Correlations – Carcass Weight

  14. 8 Age Adjusted 912 Fat Adjusted 1113 Age Adjusted 229 Fat Adjusted Carcass Weight Fat Thickness Adjusted Rank r = 0.82 Age Adjusted Rank

  15. 22 Age Adjusted 791 Marbling Adjusted 1119 Age Adjusted 464 Marbling Adjusted Carcass Weight Marbling Adjusted Rank r = 0.87 Age Adjusted Rank

  16. Correlations – Marbling

  17. 395 Age Adjusted 658 Carcass Weight Adjusted 638 Age Adjusted 319 Carcass Weight Adjusted Marbling Carcass Weight Adjusted Rank r = 0.99 Age Adjusted Rank

  18. 91 Age Adjusted 1159 Fat Adjusted 1178 Age Adjusted 384 Fat Adjusted Marbling Fat Thickness Adjusted Rank r = 0.85 Age Adjusted Rank

  19. Correlations – Ribeye Area

  20. 91 Age Adjusted 813 Carcass Weight Adjusted 1157 Age Adjusted 382 Carcass Weight Adjusted Ribeye Area Carcass Weight Adjusted Rank r = 0.90 Age Adjusted Rank

  21. 77 Age Adjusted 992 Marbling Adjusted 1161 Age Adjusted 211 Marbling Adjusted Ribeye Area Marbling Adjusted Rank r = 0.88 Age Adjusted Rank

  22. 65 Age Adjusted 621 Fat Adjusted 1025 Age Adjusted 511 Fat Adjusted Ribeye Area Fat Thickness Adjusted Rank r = 0.97 Age Adjusted Rank

  23. Correlations – Percent Retail Cuts

  24. 276 Age Adjusted 768 Carcass Weight Adjusted 360 Age Adjusted 71 Carcass Weight Adjusted Percent Retail Cuts Carcass Weight Adjusted Rank r = 0.96 Age Adjusted Rank

  25. 110 Age Adjusted 973 Marbling Adjusted 1247 Age Adjusted 265 Marbling Adjusted Percent Retail Cuts Marbling Adjusted Rank r = 0.88 Age Adjusted Rank

  26. Fat Thickness Adjusted Rank Age Adjusted Rank Percent Retail Cuts r = 0.60

  27. 2, 6, 8 22 21 Top 2% 59 82 Top 7% 104 169 269 288 517 1005 Bottom 21% 1256 Bottom 1% 1266 Sires Fat Adjusted 1266 Sires Age Adjusted

  28. Reranking of Sires - PRC 0.96 CWT Adjusted 1 2 14 6 4 3 7 5 10 9 0.88 Marb Adjusted 220 4 639 5 3 6 2 1 53 11 0.60 Fat Adjusted 22 2 517 104 6 59 8 288 269 169 Age Adjusted 1 2 3 4 5 6 7 8 9 10

  29. Summary • Carcass endpoint does alter ranking • Sometimes significantly • What is the solution? • Different EPDs for different endpoints? • Change all EPDs to a different endpoint? • Do nothing?

  30. Genetic Evaluation of Carcass Data Using Age, Weight, Fat, or Marbling Endpoints 2003 BIF Selection Decisions Committee May 29, 2003 Janice M. Rumph Montana State University – Bozeman

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