Genetic Correlation Between Body Weights and Frame Size Measures in Hanwoo

The objective of this study was to estimate genetic correlation between body weight traits and frame size measurement traits of three different types of age adjustment in Hanwoo bulls and steers raised at test station in South Korea. Body weights and ten frame size measurement records on 6,832 bulls and 5,916 steers born between 1996 and 2013 and raised at Hanwoo test station from six months of age were collected. Body weights were linearly adjusted to 365 days (YW), 548 days (BW18) and 730 days (BW24) of ages. Multi-trait animal models included test batch as a fixed contemporary group effect and animal’s genetic effect as random. Variance components were estimated using REMLF90. Body weight reached 52% at yearling compared to the body weight at 24 months of age while frame size measures reached 75-87% at yearling depending on measurement position. Heritability estimates of body weights were moderate; YW 0.34-0.41, BW18 0.35-0.38, and BW24 0.35-0.38. Heritability estimates of stature (wither height or hip height) were somewhat higher (0.36-0.49) than those of chest volume (chest girth, depth and width of chest), body length or rump volume (rump or pelvic widths, rump length or hip bone width) measurement traits were moderate; 0.26-0.55 at yearling, 0.24-0.38 at 18mo of age, and 0.24-0.49 at 24mo of age. Genetic correlation between body weight traits and frame size traits were high. Genetic correlation between body weight traits and stature traits were rather stable over the ages; 0.45 to 0.70. However, the genetic relationships of the other frame size traits with body weight traits became higher as animals grew. Chest or rump volume traits except chest girth measured at yearling were moderately correlated genetically with BW18 (0.33 to 0.54) or with BW24 (0.30 to 0.51). Chest or rump volume size traits except chest girth measured at 18 or 24 mo of ages were highly correlated genetically with BW18 (0.48 to 0.75) or with BW24 (0.45 to 0.74). Chest girth measured at three age groups had high genetic correlations with body weight traits (0.61 to 0.85). To conclude, overall skeletal size traits - wither height, hip height and body length are moderately to highly correlated genetically with body weight traits without great differences over ages. Chest or rump volume size traits measured later than yearling age reflect the individual differences in the degree of fattening, thus changing the genetic relationships with body weight traits.