Abstract
MCSU (molybdenum cofactor sulfurase) deficiency is a xanthine metabolic disorder controlled by autosomal recessive gene in the Japanese Black cattle. The association among the mutant allele (m) of MCSU deficiency and carcass traits was investigated. The MCSU genotypes were diagnosed in 317 fattened steers whose either father, grandfather, or great-grandfather was the carrier sire. The steers were composed of 240 normals (MM) and 77 carriers (Mm) . The association analysis was carried out by two different approaches, i.e., using adjusted carcass records based on BLUE for non-genetic factors of shipping year, fattening farm, fattening period and slaughter age, and using unadjusted carcass records. In the former approach the BLUE were preliminarily obtained by using 48, 045 carcass records. On the other hand, the non-genetic factors were included in the model in the latter approach. The significance testing for the MCSU genotype was based on the GLMTEST program that handles the hypothesis tests for fixed effects under animal models. While the association among the MCSU genotype and carcass traits was not significant in carcass weight, daily gain, longissimus muscle area, rib thickness and subcutaneous fat thickness, only BMS number showed the significant (p<0.05) decreased effect in both approaches.
