Variations in the insulin receptor substrate 1 (IRS1) and its association with growth traits in Chinese black Tibetan sheep (Ovis aries).

This paper presented the results on the study of insulin receptor substrate 1 (IRS1) polymorphisms in Chinese black Tibetan sheep. Via DNA direct sequencing, four variations within 3' untranslated region (UTR) of IRS1, including g.9382T > G, g.9569T > G, g.9572C > T and g.9695A > C were detected in the black Tibetan sheep population. Based on the χ2 test, those four loci deviated from Hardy-Weinberg equilibrium (p < 0.05). In g.9569T > G locus, genotype of GG possessed advantage on body weight (p < 0.05). In g.9572C > T locus, individuals with genotype of TT homozygous mutation decreased significantly on body weight, withers height, body length and chest circumference (p < 0.05 or p < 0.01). In g.9695A > C locus, the body weight and chest circumference were also higher in AA carriers than in CC carriers (p < 0.05). Our results provided evidence that polymorphisms in IRS1 were associated with growth efficiency traits by quantitative genetic analysis, and may be used for marker-assisted selection in Chinese indigenous sheep.