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Defective appearances, including white spotting (WS), tongue defect (TD), and nipple defect (ND), in Japanese Black cattle potentially lead to economic losses to farmers in Japan. We estimated genetic parameters of defective appearances using 553,433 records of Japanese Black heifer calves housed in the Kagoshima Prefecture. Variance and covariance were estimated using the Gibbs sampling algorithm. The estimated heritability ranged from 0.29 for TD to 0.76 for WS. Percent breeding value (%BV) estimates indicated high variation in WS and ND among sires, reflecting higher heritability. Furthermore, there was a positive linear relationship between the %BV estimate of a sire and the mean incidence rate of each defect in his female offsprings. TD was positively associated with other defects. Therefore, genetic factors strongly affect the incidence of defective appearances in Japanese Black cattle. [ABSTRACT FROM AUTHOR]

The objective of this study was to estimate genetic parameters for first calving reproductive traits and growth curve characteristics in Japanese Black cattle. The Gompertz growth function was fitted to body weight–age data to obtain the mature weight (MWT) and rate of maturing (ROM) of cows. Data of reproductive traits including the first service conception rate (CR) for heifers, age at the first calving (AFC), and gestation length for the first calving were collected. Records of 3,204 animals were used for analysis. Genetic parameters were estimated using a linear uni- and bivariate animal model. The heritability estimates were moderate (0.29 for ROM) and high (0.57 for MWT) for growth curve parameters and low (0.03–0.11) for reproductive traits. There was a negative genetic correlation between MWT and ROM (−0.26), suggesting that an animal with a faster ROM would show a lower MWT. CR was negatively correlated with MWT (−0.42) but significantly and positively correlated with ROM (0.91). There was a negative genetic correlation between AFC and MWT (−0.49). These results suggest that a heifer with a faster ROM and lower MWT would show a higher CR. Meanwhile, a heifer with a lower MWT would show a higher AFC. [ABSTRACT FROM AUTHOR]