抄録
The Kumamoto sub-breed of Japanese Brown cattle is famous for its heavy carcass weight, and increasing carcass weight is
one of the most important breeding goals for this sub-breed. Genetic approaches may be especially useful for breeding this cattle
and improving its traits. In this study, we elucidated the genetic characteristics of the Kumamoto sub-breed by analyzing the
genotype and allele frequencies of DNA polymorphisms. Seven DNA polymorphisms were selected from the SREBP1 , SCD,
FASN, EDG1, NCAPG, LYST , and F11 genes, which affect economically important traits. For genotyping, 112 offspring of 19 sires
were collected. Our genotyping results show an extremely low allele frequency of the S allele of SREBP1, which affects fatty acid
composition in intramuscular fat, in the Kumamoto sub-breed. Therefore, this polymorphism might not be useful for enhancing the
breeding of this sub-breed. The causative mutation of LYST was not detected in our sampling population, suggesting a lower risk of
Chediak-Higashi syndrome in the Kumamoto sub-breed. On the other hand, the Kumamoto sub-breed possessed high frequencies
of desirable alleles of the SCD and NCAPG genes, which affect fatty acid composition and carcass weight, respectively, possibly
because of artificial selection. Hence, these DNA markers could be used to improve economically important traits of the
Kumamoto sub-breed. Our results also indicate that the causative mutation of factor XI deficiency might be common in the
population because multiple sires were carriers of this disease. Since this disease may cause fetal losses, elimination of this disease
from the Kumamoto sub-breed would be desirable.
