Comparison of the effects explained by variations in the bovine PLAG1 and NCAPG genes on daily body weight gain, linear skeletal measurements and carcass traits in Japanese Black steers from a progeny testing program.

The c.1326T>G single nucleotide polymorphism (SNP) in the NCAPG gene, which leads to an amino acid change of Ile442 to Met442, was previously identified as a candidate causative variation for a bovine carcass weight quantitative trait loci (QTL) on chromosome 6, which was associated with linear skeletal measurement gains and daily body weight gain at puberty. Recently, we identified the stature quantitative trait nucleotides (QTNs) in the PLAG1-CHCHD7 intergenic region as the causative variations for another carcass weight QTL on chromosome 14. This study aimed to compare the effects of the two QTL on growth and carcass traits using 768 Japanese Black steers from a progeny testing program and to determine whether a genetic interaction was present between them. The FJX_250879 SNP representing the stature QTL was associated with linear skeletal measurements and average daily body weight gain at early and late periods during adolescence. A genetic interaction between FJX_250879 and NCAPG c.1326T>G was detected only for body and rump lengths. Both were associated with increased carcass weight and Longissimus muscle area, and NCAPG c.1326T>G was also associated with reduced subcutaneous fat thickness and increased carcass yield estimate. These results will provide useful information to improve carcass weight in Japanese Black cattle.