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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 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 • Few producers kill cattle based on an age constant • Back Fat • Carcass Weight • Marbling
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 ?
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)
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
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
Other Traits • Ribeye Area • Had to be greater than 6 in2 • Percent Retail Cuts • Had to be between 40 – 60%
Estimates of Heritability Trait Adjustment
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
9 Age Adjusted 1000 Marbling Adjusted 988 Age Adjusted 92 Marbling Adjusted Fat Thickness Marbling Adjusted Rank r = 0.85 Age Adjusted Rank
8 Age Adjusted 912 Fat Adjusted 1113 Age Adjusted 229 Fat Adjusted Carcass Weight Fat Thickness Adjusted Rank r = 0.82 Age Adjusted Rank
22 Age Adjusted 791 Marbling Adjusted 1119 Age Adjusted 464 Marbling Adjusted Carcass Weight Marbling Adjusted Rank r = 0.87 Age Adjusted Rank
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
91 Age Adjusted 1159 Fat Adjusted 1178 Age Adjusted 384 Fat Adjusted Marbling Fat Thickness Adjusted Rank r = 0.85 Age Adjusted Rank
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
77 Age Adjusted 992 Marbling Adjusted 1161 Age Adjusted 211 Marbling Adjusted Ribeye Area Marbling Adjusted Rank r = 0.88 Age Adjusted Rank
65 Age Adjusted 621 Fat Adjusted 1025 Age Adjusted 511 Fat Adjusted Ribeye Area Fat Thickness Adjusted Rank r = 0.97 Age Adjusted Rank
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
110 Age Adjusted 973 Marbling Adjusted 1247 Age Adjusted 265 Marbling Adjusted Percent Retail Cuts Marbling Adjusted Rank r = 0.88 Age Adjusted Rank
Fat Thickness Adjusted Rank Age Adjusted Rank Percent Retail Cuts r = 0.60
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
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
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?
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