QTL and candidate genes associated with heifer pregnancy rate and stayability in beef cattle

Abstract Text: It has long been recognized that marker assisted selection offers considerable promise over traditional selection for low heritability and difficult to measure traits like fertility. The objectives of this study were to map quantitative trait loci (QTL) and identify candidate gene(s) associated with heifer pregnancy rate and stayability in beef cattle populations. A Bayes-B model was used to simultaneously analyze 54,555 SNP markers and from those analyses QTL were identified by characterizing the proportion of additive genetic variation explained by every non-overlapping 1-Mb region of the genome. There were 4 significant 1-Mb windows located on BTA24 in the region from 25 to 31 Mb for heifer pregnancy rate, and these cumulatively explain 6.1% of additive genetic variance in the Black Angus population. Two significant 1-Mb QTL located on BTA6 at 40 and 71 Mb were identified for stayability in the Simmental population and explained 1.4% and 6.3% of additive genetic variances, respectively. The identified QTL regions harbor very promising candidate genes (Cadherin and AUTS2 genes for heifer pregnancy rate and KIT and SLIT genes for stayability) in their corresponding populations. Further investigations are needed to identify the causal variants harbored within the identified regions of the genome. Once found, knowledge of such mutations would create new opportunities for the selection of more fertile animals.

Keywords: Beef cattle, Stayability, Marker, QTL, candidate gene