Loci associated with spontaneous abortion in primiparous Holstein cattle.

Abstract

INTRODUCTION: Spontaneous abortion (SA) in cattle refers to pregnancy loss occurring between days 42 and 260 of gestation. SA is costly, inefficient, and often leads to premature culling of cows. METHODS: This study aimed to identify loci associated with SA in primiparous Holstein cows by conducting a genome-wide association analysis of cows bred via artificial insemination (AI; 679 controls and 69 cases that aborted) or that were embryo transfer (ET) recipients (236 controls and 41 cases) from a single dairy. RESULTS: In AI-bred cows, 86 loci (413 single nucleotide polymorphisms or SNPs) and 168 positional candidate genes were associated (FDR <0.05) with SA, while in ET recipients, 4 loci (10 SNPs) and 16 positional candidate genes were associated (FDR <0.05) with SA. No SA-associated loci were shared between AI-bred or ET recipient cows, but nine associated loci (FDR <0.05) in AI-bred cows were shared with AI-bred heifers. DISCUSSION: The difference in loci associated with AI-bred and ET recipient cattle may be due to differences in mechanisms associated with the maintenance of pregnancy betweenandderived embryos, or a larger sample size may be needed to identify additional shared loci. Identifying loci associated with SA in AI-bred and ET recipient cows provides an opportunity to enhance selection for reproductive efficiency in Holstein cattle.