Genomic Regions Associated with Spontaneous Abortion in Holstein Heifers

<b>Background/Objectives:</b> The dairy industry relies on reproductive efficiency to maintain efficient milk production. Spontaneous abortion (SA), defined as pregnancy loss between gestation days 42 and 260, occurred in 4.5% of the artificially inseminated (AI) Holstein heifers and 31.6% of the embryo transfer (ET) recipient Holstein heifers that received in vitro-produced frozen embryos on a single dairy farm in Idaho. <b>Methods:</b> A genome-wide association analysis (GWAA) was performed to identify the associations (FDR <i>p</i> < 0.05) with SA in heifers that were bred by AI (1351 controls that delivered at term and 63 cases that aborted) that conceived following the first insemination, as well as in 59 controls and 273 cases of ET recipient heifers pregnant from the first ET. <b>Results:</b> There were 216 loci and 413 positional candidate genes associated (FDR <i>p</i> < 0.05) with SA in the heifers bred by AI in a recessive model and no loci associated with SA in the ET recipients. <b>Conclusions:</b> The identification of loci associated with SA in the heifers bred by AI may be used to reduce fetal loss through genomic selection.