Characteristics of Physiological Parameters of Japanese Black Calves Relate to Carcass Weight

SIMPLE SUMMARY: Withers height and chest girth in calves were significantly correlated with carcass weight and body weight, regardless of sex. Meanwhile, the relationship between blood metabolites and carcass weight differed according to sex. Body measurements and blood metabolites measured during the growing period could be used to determine the nutritional and physiological status of cattle and predict the final carcass weight, but the animal factor, such as sex, should be considered. ABSTRACT: This study aimed to identify the growth performance and blood factors associated with carcass weight in Japanese Black calves based on 675 performance tests and field carcass records. We measured the body weight, withers height, and chest girth at the start of fattening age (approximately 8–10 months) and analyzed eight blood factors, including vitamins and metabolites. Single- and two-trait animal models were used to estimate the heritability and genetic correlations. The heritability estimates for growth performance were moderate to high (ranging from 0.48 to 0.74), and those for blood metabolites were low to moderate (ranging from 0.19 to 0.51). Estimates for genetic correlations of carcass or body weight with body weight, withers height, and chest girth were high (ranging from 0.42 to 0.80). The body weight and withers height at 8 months of age are possibly closely related to the final carcass weight. The blood metabolites associated with body weight were vitamin E in steers (castrated males) and β-carotene in heifers. Our findings indicate that body measurements and blood metabolites measured during the growing period could be used to determine the nutritional and physiological status of cattle as well as predict carcass weight.