Evaluation of genetic structure across U.S. climate zones using prominent AI sires of Red Angus cattle

Abstract

Climate variability can influence cattle performance. Therefore, the objective of this research was to determine fine-scale genetic diversity in Red Angus cattle in relation to climate zones. One hundred and seventy-five prominent Red Angus artificial insemination (AI) sires were sampled from five conterminous U.S. climate regions (Cool Arid, Cool Humid, Transition Zone, Warm Arid, and Warm Humid). Quantitative and molecular genetic approaches were used to evaluate genetic diversity for the cattle. The first method utilized neutral SNP to determine the genetic structure of the population. The second method used 66 SNP associated with traits potentially influenced by climate (body weight, heat stress, milk yield, heifer conception rate, and early embryonic survival) to detect loci under selection in each zone. Using 13,961 SNP, the genetic structure analysis revealed that there were eight sub-populations present within Red Angus. Furthermore, 23 of the 66 SNP were not in Hardy-Weinberg Equilibrium and loci under selection tests (P < 0.05). Chi-square tests revealed 7 of the 23 SNP to differ (P < 0.008) among climate zones. In conclusion, fine genetic substructure observed in Red Angus corresponded to U.S. climate zones. By identifying the genetic diversity within a prominent Bos taurus beef breed in relation to climate, management strategies can be implemented to utilize the genetic diversity of this breed to adapt to changing climates.