Abstract #470

# 470
Association between lipid-related genes implicated in conceptus elongation and female fertility traits in dairy cattle.
R. Abdollahi-Arpanahi*1, M. R. Carvalho2, E. S. Ribeiro2, F. Peñagaricano1, 1University of Florida, Gainesville, FL, 2University of Guelph, Guelph, ON, Canada.

Elongation of the preimplantation conceptus is a requirement for pregnancy success in ruminants, and failures in this developmental phase seem to be highly associated with subfertility in dairy cattle. Identifying genetic markers that are related to early conceptus development and survival, and utilizing these markers in selective breeding can improve reproductive efficiency of dairy herds. The objective of this study was to evaluate the association of 1,679 single nucleotide polymorphisms (SNPs) within or close to 183 candidate genes involved in lipid metabolism of the elongating bovine conceptus with different female fertility traits in US Holstein dairy cattle. A total of 27,371 Holstein bulls with predicted transmitting ability (PTA) records for daughter pregnancy rate (DPR), cow conception rate (CCR), and heifer conception rate (HCR) were used as discovery population. The associations found in the discovery population were validated using 2 female Holstein populations (1,122 heifers and 2,138 cows) each with 4 fertility traits, including success to first insemination (SF), number of services per conception (NSC), fertility categorization (FertC), and age at first conception (AFC) for heifers or days open (DO) for cows. Marker effects were estimated using a linear mixed model with SNP genotype as a linear covariate and a random polygenic effect. After multiple testing correction, 39 SNPs flagging 27 candidate genes were associated with at least one fertility trait in the discovery population. Of these 39 markers, 3 SNPs were validated in the heifer population and 4 SNPs were validated in the cow population. The 3 SNPs validated in heifers are located within or near genes CAT, MYOF, and RBP4 while the 4 SNPs validated in lactating cows are located within or close to genes CHKA, GNAI1, and HMOX2. These validated genes seem to be relevant for reducing pregnancy losses, and the SNPs within these genes are excellent candidates to be included into genomic tests for improving reproductive performance in dairy cattle. Our findings emphasize the importance of lipid metabolism for bovine conceptus development.

Key Words: conceptus development, reproductive trait, validation study