Genetic correlation between live body measurements and beef cutability traits in Hanwoo steers.
OBJECTIVE
The growth, carcass and retail cut yield records on 1,428 Hanwoo steers obtained through progeny testing were analyzed in this study, and their heritability and genetic relationships among the traits were estimated using animal models.


METHODS
Two different models were compared in this study. Each model was fitted for different fixed class effects, date of slaughter for carcass traits and batch of progeny test live measurement traits, and a choice of covariates (carcass weight in Model 1 or backfat thickness in Model 2) for carcass traits.


RESULTS
The differences in body composition among individuals were deemed being unaffected by their age at slaughter, except for carcass weight and backfat thickness. Heritability estimates of body size measurements were 0.21 to 0.36. Heritability estimates of retail cut percentage were high (0.56 from Model 1 and 0.47 from Model 2). And the heritability estimates for loin muscle percentage were 0.36 from Model 1 and 0.42 from Model 2, which were high enough to consider direct selection on carcass cutability traits as effective. The genetic correlations between body size measurements and retail cut ratio (RCR) were close to zero. But, some negative genetic correlations were found with chest girths measured at yearling (Model 1) or at 24 months of age or with chest widths. Loin muscle ratio (LMR) was genetically negatively correlated with body weights or body size measurements, in general in Model 1. These relationships were low close to zero but positive in Model 2. Phenotypic correlation between cutability traits (RCR, LMR) and live body size measurements were moderate and negative in Model 1 while those in Model 2 were all close to zero.


CONCLUSIONS
Therefore, the body weights or linear body measurements at an earlier age may not be the most desirable selection traits for exploitation of correlated responses to improve loin muscle or lean meat yield.
Division of Animal Breeding & Genetics, National Institute of Animal Science, Cheonan 31000, Korea.
Yun Ho
YH
Choy
Division of Animal Breeding & Genetics, National Institute of Animal Science, Cheonan 31000, Korea.
Jae Goo
JG
Lee
Division of Animal Breeding & Genetics, National Institute of Animal Science, Cheonan 31000, Korea.
Alam
A
Mahboob
Division of Animal Breeding & Genetics, National Institute of Animal Science, Cheonan 31000, Korea.
Tae Jeong
TJ
Choi
Hanwoo Improvement Center, National Agricultural Cooperative Federation, Seosan 31948, Korea.
Seung Hee
SH
Rho
Carcass; Genetic Correlation; Hanwoo; Heritability; Linear Measurement; Retail Cut