A Study on Genetic Parameters of Carcass Weight and Body Type Measurements in Hanwoo Steer

This study was conducted to estimate heritabilities and genetic correlations among carcass weight and body type measurements (Wither height, Rump height, Body length, Chest depth, Chest width, Rump length, Rump width, Thurl width, Hipbone width, Chest girth) obtained from 1,587 records of Hanwoo steers in National Hanwoo Contest. Based on EM-REML algorithm, this study estimated genetic parameters of the carcass weight and body type measurements that greatly affect Hanwoo's carcass grade and body type. The means and standard deviations of each trait were 377.30±45.59 kg, 136.14±4.51 cm, 137.79±4.62 cm, 157.77±6.97 cm, 77.55±3.62 cm, 51.72±4.30 cm, 55.04±3.19 cm, 50.21±2.96 cm, 48.29±2.94 cm, 29.12±2.04 cm, and 217.31±11.36 cm for Carcass weight, Wither height, Rump height, Body length, Chest depth, Chest width, Rump length, Rump width, Thurl width, Hipbone width and Chest girth, respectively. As a result of analysis on the effects by the birth year, the Carcass weight, Wither height, Rump height, Body length, Chest depth, Chest width, Rump length, Rump width, Thurl width, and Chest girth came out highest as 413.4±37.5 kg, 138.4±4.1 cm, 139.9±4.3 cm, 162.1±5.7 cm, 80.8±2.5 cm, 55.3±3.7 cm, 58.0±3.3 cm, 52.9±2.4 cm, 50.9±2.8 cm and 225.9±8.3 cm, respectively in 2005. As a result of analysis on the effects by the birth season, the carcass weight and body type measurements came out highest, respectively in spring. As a result of the analysis on the effects by the birth location, all of the traits came out highest, respectively in Gangwon. In the majority of carcass weights and body type measurements, statistically significant differences were observed depending on the location of birth. The heritabilities of the carcass weight, chest width and chest girth were estimated as 0.242, 0.221 and 0.264 respectively. These heritabilities of such traits were higher than those of other traits (withers height, rump height, body length etc.). Genetic correlation coefficients were estimated to be 0.944 between wither height and rump height, 0.822 between carcass weight and chest width, 0.769 between carcass weight and chest girth. From the results above, if the carcass weight should be improved by body type measurements of Hanwoo steer, it seemed that such factors as, chest width, chest girth, body length and withers height, which have relatively higher genetic correlations with carcass weight, should be considered.