Title: Association of STAT2 SNP genotypes and growth phenotypes in heifers from an Angus, Brahman and Romosinuano diallel population Authors
Submitted to: Western Section of Animal Science Proceedings
Publication Type: Proceedings
Publication Acceptance Date: May 1, 2013
Publication Date: June 1, 2013
Citation: Luna, P., Lopez, P., Rincon, G., Riley, D.G., Chase, C.C., Jr., Medrano, J.F., VanLeeuwen, D., Silver, G.A., Thomas, M.G. 2013. Association of STAT2 SNP genotypes and growth phenotypes in heifers from an Angus, Brahman and Romosinuano diallel population. Proceedings, Western Section, American Society of Animal Science. 64:194-197. Technical Abstract: Components of the growth endocrine axis regulate growth and reproduction traits in cattle. A SNP in the promoter of the signal transducer and activator of transcription 2 (STAT2) has been previously reported to be associated with postpartum rebreeding in a diallel beef population composed of 650 heifers from Angus, Brahman, and Romosinuano breeds. The objective herein was to assess the association between STAT2 SNP (i.e., -rs137066603-A/G-) genotypes and growth traits such as birth weight, weaning weight, and yearling weight in this multi-breed heifer population. This SNP had minor allele frequency > 10% across the three breeds and did not deviate from HardyWeinberg equilibrium (X2 = 1.00, P > 0.31). Genotype to phenotype association analyses used a mixed effects model that included phenotype as the response variable, genotype as a fixed term, sire as a random term, and coefficient of ancestry as a covariate. Although these analyses did not reveal any significant association between the STAT2 genotypes and growth phenotypes, the traits birth weight, weaning weight, and yearling weight were associated (P < 0.05) with the interaction of SNP genotype and ancestral cluster. A population stratification analysis involving 72 informative SNPs identified the ancestral cluster 1 (inferred primarily from Brahman), and clusters 2 and 3 (inferred primarily from Bos taurus). The interaction plots revealed a higher estimated effect of heterozygous genotype in cluster 1 and lower estimates in clusters 2 and 3, as this genotype increased the levels of the traits birth weight (7.4 ± 0.7 kg), weaning weight (69.9 ± 6.4 kg) and yearling weight (72.4 ± 4.5 kg). Like associative analyses with fertility traits, a SNP in the promoter of the STAT2 gene was associated with growth traits in an admixed heifer population composed of Angus, Brahman and Romosinuano breeds. This study suggests a non-additive genetic effect as the heterozygote appeared to be the favorable genotype.