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 Many breed associations are printing some form of carcass EPDs Based on an age constant Based on an age constant Few producers kill cattle based on an age constant Few producers kill cattle based on an age constant Back Fat Back Fat Carcass Weight Carcass Weight Marbling 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) 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) 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 15,770 – Percent Retail Cuts 12,056– Marbling 8586 – Ribeye Area 8382 – Fat Thickness 18,133 animals in pedigree

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

Other Traits Ribeye Area Ribeye Area Had to be greater than 6 in 2 Had to be greater than 6 in 2 Percent Retail Cuts Percent Retail Cuts Had to be between 40 – 60% Had to be between 40 – 60%

Results

Estimates of Heritability FatMarbCWTREAPRC Age Fat Marb CWT Trait Adjustment

Correlations – Fat Thickness AgeCWTMarb Age CWT-0.82 Marb-

Fat Thickness Age Adjusted Rank Carcass Weight Adjusted Rank r = Age Adjusted 915 Carcass Weight Adjusted 651 Age Adjusted 186 Carcass Weight Adjusted

Fat Thickness Age Adjusted Rank Marbling Adjusted Rank r = Age Adjusted 1000 Marbling Adjusted 988 Age Adjusted 92 Marbling Adjusted

Correlations – Carcass Weight AgeFatMarb Age Fat-0.81 Marb-

Carcass Weight Age Adjusted Rank Fat Thickness Adjusted Rank r = Age Adjusted 912 Fat Adjusted 1113 Age Adjusted 229 Fat Adjusted

Carcass Weight Age Adjusted Rank Marbling Adjusted Rank r = Age Adjusted 791 Marbling Adjusted 1119 Age Adjusted 464 Marbling Adjusted

Correlations – Marbling AgeCWTFat Age CWT-0.85 Fat-

Marbling Age Adjusted Rank Carcass Weight Adjusted Rank r = Age Adjusted 658 Carcass Weight Adjusted 638 Age Adjusted 319 Carcass Weight Adjusted

Marbling Age Adjusted Rank Fat Thickness Adjusted Rank r = Age Adjusted 1159 Fat Adjusted 1178 Age Adjusted 384 Fat Adjusted

Correlations – Ribeye Area AgeCWTMarbFat Age CWT Marb-0.87 Fat-

Ribeye Area Age Adjusted Rank Carcass Weight Adjusted Rank r = Age Adjusted 813 Carcass Weight Adjusted 1157 Age Adjusted 382 Carcass Weight Adjusted

Ribeye Area Age Adjusted Rank Marbling Adjusted Rank r = Age Adjusted 992 Marbling Adjusted 1161 Age Adjusted 211 Marbling Adjusted

Ribeye Area Age Adjusted Rank Fat Thickness Adjusted Rank r = Age Adjusted 621 Fat Adjusted 1025 Age Adjusted 511 Fat Adjusted

Correlations – Percent Retail Cuts AgeCWTMarbFat Age CWT Marb-0.54 Fat-

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

Percent Retail Cuts Age Adjusted Rank Marbling Adjusted Rank 110 Age Adjusted 973 Marbling Adjusted r = Age Adjusted 265 Marbling Adjusted

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

1266 Sires Age Adjusted 1266 Sires Fat Adjusted 1256 Bottom 1% 82 Top 7% 21 Top 2% 1005 Bottom 21% , 6, 8

Reranking of Sires - PRC Age Adjusted CWT Adjusted Marb Adjusted Fat Adjusted

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