|THOMAS, MILTON - Colorado State University|
|Wilson, Carrie - Welsh|
|SPEIDEL, SCOTT - Colorado State University|
|ENNS, MARK - Colorado State University|
|PAIVA, SAMUEL - Embrapa Genetic Resources|
Submitted to: Livestock Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/15/2019
Publication Date: 4/18/2019
Citation: Krehbiel, B.C., Thomas, M.G., Wilson, C.S., Speidel, S.D., Enns, M.R., Paiva, S.R., Blackburn, H.D. 2019. Evaluation of genetic structure across U.S. climate zones using prominent AI sires of Red Angus cattle. Livestock Science. 225:26-31. https://doi.org/10.1016/j.livsci.2019.04.012.
Interpretive Summary: Climate variability can influence cattle performance. Therefore, the objective of this research was to determine the genetic variation of 175 Red Angus artificial insemination (AI) sires sampled from five climate zones in the U.S. (Cool Arid, Cool Humid, Transition Zone, Warm Arid, and Warm Humid). The sires were analyzed at molecular markers potentially impacted by climate (e.g. body weight, heat stress). Results showed genetic diversity of cattle that corresponded to the U.S. climate regions, suggesting natural selection caused by environment. Ultimately, the genetic diversity identified in the prominent Red Angus AI sires could be utilized to adapt the breed to varying climatic conditions.
Technical 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.