QTL Analysis for Gestation Period in Japanese Black Cattle

Fertility is one of the most important traits in beef cattle. In Japanese Black cattle, gestation period becomes longer. A rate of dystocia is increasing, because of the bigger fetus and the longer gestation period. To identify genetic loci linked to gestation period in Japanese Black cattle, we performed QTL analysis using three paternal half-sib families comprised of 282, 287, and 287 steers. These families were genotyped using the Illumina Bovine3K BeadChip. Four, two, and three QTLs of gestation period were detected in three families (<5% chromosome-wise level), respectively. Two of these QTLs, locating on BTA4 and BTA13, were detected in two families. These QTLs were 5% experiment-wise significant level in one family. We performed an association study for these two chromosomes, using 179 Japanese Black cows and Illumina BovineHD BeadChip. Gestation period was associated with SNPs located in a QTL on BTA4 (P=2.8E-05). Therefore, we concluded that the QTL of gestation period was located on BTA 4, from 99 to 102 Mb on the UMD3.1 assembly. These results may be useful to marker-assisted selection to improve the gestation period in Japanese Black cattle.