Estimates of genetic parameters were obtained for body measurement traits of 648 animals at 4 months of age, of 545 at 8 months and carcass traits of 14 972 animals with the use of an animal model by the restricted maximum likelihood procedure. The estimated heritabilities for carcass traits were high (0.41 to 0.54). At 4 months the estimated direct heritabilities for body measurement traits were moderate to high (0.28 to 0.64), except for chest width (0.19); at 8 months they were also moderate to high (0.23 to 0.49), except for chest depth and chest width (0.18 and 0.06, respectively). Maternal heritabilities for all body measurement traits were low at both ages. The results indicate that because of their moderate direct genetic correlations with body measurement traits, carcass weight, rib thickness and subcutaneous fat thickness can be improved; however, rib eye area and beef marbling standard show little such possibility considering their correlation with body measurement traits.

No abstract

This study was conducted to evaluate the importance of maternal effect on body measurement traits at an early stage of growth, and to estimate the genetic relationships between direct and maternal effects and among body measurement traits at 0 month (0-mo) and 4 months (4-mo) of age in a population of Japanese Black calves. Body measurements and body weight of 889 Japanese Black calves were estimated with the use of an animal model by the Residual Maximum Likelihood procedure. Direct heritabilities were low to moderate, ranging between 0.17 ± 0.09 and 0.48 ± 0.13 at 0-mo, and slightly lower, ranging between 0.15 ± 0.07 and 0.33 ± 0.13 at 4-mo. Estimated maternal heritabilities were low to moderate, ranging between 0.08 ± 0.07 and 0.33 ± 0.07 at 0-mo and 0.13 ± 0.06 to 0.33 ± 0.06 at 4-mo. The direct genetic correlations between 0-mo and 4-mo were moderate to highly positive, ranging from 0.53 ± 0.23 to 0.96 ± 0.09. The estimated direct genetic correlation of chest width with other width traits was low and positive at both ages, whereas with hip width it was high and positive (0.80 ± 0.09) at 0-mo, suggesting that simultaneous improvement of body width of the front and back parts is possible. Maternal genetic effects were relatively independent of direct genetic effects for body measurement traits and can be considered in genetic evaluation.