PSXV-3 Genome-Wide Association Study for Sweat Gland Area in Multi-Breed Brahman-Angus Population

Abstract

Thermal stress in subtropical regions is a major limiting factor in beef cattle productions with around $370 million being lost annually due to reduced performance. About 45% of beef cattle in the United States are in the southern and southeastern states where tropical and subtropical climates are most prevalent. Cattle utilize sweating to dispense most of their excess heat allowing them to return to their thermoneutral zone. The objective of this study was to conduct a genome-wide association study on sweat gland area in the Multi-breed Angus-Brahman herd of the University of Florida. Skin samples were collected along the shoulder from 337 cows of varying Brahman and Angus percentages. Cows were genotyped with the Bovine GGP F250k array. The biopsies were processed into histology slides and then ImageJ software was used to measure sweat gland area. A general linear model was used to test the significance of breed composition and age group on sweat gland area. Breed composition and age group had a significant effect on sweat gland area (P < 0.0001 and P < 0.0001, respectively), with sweat gland area increasing with Brahman percentage. Quality control was conducted using BLUPF90 software including a call rate of 0.90 and a minor allele frequency of 0.01 which left 125,035 SNPs available for the single-step genome wide association analysis. BLUPF90 software was used to fit a single locus mixed model to test the effect of each marker. There were a significant SNPs located in the MINDY1 and PRUNE1 gene, which are involved in cell proliferation and induction of cell motility. These results show that with selection on these SNPs, can improve the ability of cattle to adapt to thermal stress.