PSVI-13 Genomic analysis of pregnancy outcome in Brangus heifers.

Abstract Reproductive efficiency is a critical factor in beef cattle production, where failure to conceive or late conception leads to economic losses by increasing resource consumption without optimal productivity. Genetic selection for fertility traits can enhance reproductive performance, yet these traits typically exhibit low to moderate heritability (0.07–0.21 for pregnancy outcomes). Despite these relatively low heritability estimates, genomic selection has proven effective in accelerating genetic gain. This study aimed to identify quantitative trait loci (QTLs) and candidate genes associated with pregnancy outcomes in Brangus heifers. The herd was composed of 2-year-old Brangus heifers managed by Seminole Tribe of Florida Inc. (Northeast Glades, FL, USA) between 2016 and 2018. Pregnancy was diagnosed via transrectal ultrasonography, and genotyping was conducted using the Bovine GGP F250 array (GeneSeek, Inc., Lincoln, NE). After quality control, 110,912 variants, and 1,415 animals remained. Heritabilities and Genome-wide association analysis (GWAS) were conducted using the Genome-wide Complex Trait Analysis (GCTA) software. Heritability and variance components were estimated applying a REML-based approach and GWAS was conducted applying a Mixed Linear Model Association (MLMA) with a Leave-One-Chromosome-Out (LOCO) approach. The heritability of pregnancy outcome in Brangus cattle was 0.15 ± revealing a low to moderate heritability. The GWAS analysis reveals a total of 3 suggestive regions on BTA 5, 10, and 20, and 3 significant regions on BTA 13, 14, and 16. By identifying heritability estimates and genetic markers (QTLs), this research supports genomic selection strategies to enhance fertility and sustainability in beef cattle production.