0009 Evaluation of genetic structure across five U.S. climate zones using prominent AI sires of two British Bos taurus breeds.

Cattle performance in diverse climates can be problematic if they cannot adapt to climate variability. Previous research showed Hereford cattle to have genetic substructure associated with U.S. climates: cool arid (CA), cool humid (CH), transition zone (TZ), warm arid (WA), and warm humid (WH). Allele frequencies of 66 SNP from BovineSNP50 (Illumina BeadChip) were associated with the following traits: mature cow body weight, heat stress, milk yield, heifer conception rate, and early embryonic survival. Knowledge of these genotype to phenotype associations were queried from CattleQTLdb. The GENALEX (6.501) software was used to estimate population genetic results. To characterize the diversity in another British Bos taurus breed, population genetic characteristics were estimated in Red Angus bulls (n = 175) that were included in the 2000 Bull Project. Similar software, climate zone regions, and SNP were used in the analyses. The number of sires in the climates zones of CA, CH, TZ, WA, and WH were 126, 32, 11, 5, and 1, respectively. We hypothesized Red Angus bulls would possess genetic substructure across the five climatic zones as observed in Hereford bulls. ARLEQUIN (3.5.2.2) software was used to estimate Hardy-Weinberg Equilibrium (HWE) and conduct an analysis of molecular variance for genotype to phenotype associations. The number of significant (P < 0.05) SNP for the traits of milk yield, early embryonic survival, and mature cow body weight were 4, 1, and 1, respectively. Based on the results and genotypes from the bulls studied in the 2000 Bull Project, we reject our hypothesis that Red Angus bulls possess genetic substructure similar to Hereford bulls across five U.S. climate zones. These results provide evidence to suggest that Red Angus cattle in the United States appear to be preferred in beef production systems in cooler climate zones, whereas Hereford cattle populate these regions as well as drier climate zones.