PSVI-10 Genome-wide association study of mature cow weight in American Angus cattle.

Abstract Mature cow weight (MWT) significantly affects cowherd profitability by directly impacting maintenance feed requirements, which constitute a significant portion of production costs. The objectives of this study were to perform genome-wide association and functional genomic analyses to better characterize the genetic background of MWT in Angus cattle. A total of 434,746 phenotypic records from 222,907 Angus cows were used for the analyses. Of these, 33,764 cows were genotyped using various single nucleotide polymorphism (SNP) panels and imputed to a common marker density of 51,395 SNPs. Quality control procedures included filtering out markers with low call rates (< 0.90), extreme deviations from Hardy–Weinberg equilibrium (>0.15), parent-progeny Mendelian conflicts >0.01, and minor allele frequency < 0.01. A final dataset of 52,575 SNPs from 33,746 animals remained after quality control for further analyses. The single-step genome-wide association study (ssGWAS) method was used in the analyses. The Bonferroni correction method was applied to adjust for multiple tests based on the number of independent chromosomal segments at the chromosome-wide level. A total of 64 significant SNPs located on 10 chromosomes were significantly associated with MWT. These SNPs were located near 116 annotated genes, including 57 protein-coding genes, 50 long non-coding RNAs, 7 microRNAs, 1 ribosomal RNA, and 1 small nuclear RNA. Additionally, 31 quantitative trait loci were associated with key traits related to production (e.g., Body weight, metabolic body weight, dry matter intake, average daily gain, and length of productive life), meat and carcass (e.g., Bone weight, carcass weight, connective tissue amount, lean meat yield, longissimus muscle area, muscle creatine content), health (Tick resistance), milk production (Milk iron content, milk fat percentage, milk C14, C16, C18 indices, milk acid content), and reproduction (Calving index). These results contribute to a better understanding of the genomic regions associated with MWT in Angus cattle.