Abstract：Bovine insulin-like growth factorsⅠreceptor(IGF-IR), m-calpain(CAPN Ⅱ) and uncoupling protein 3(UCP 3) loci were evaluated for associations with growth traits in Nanyang population by PCR-RFLP. Only two individuals with genotype BB were detected at IGF-IR/TaqⅠloci, allele A at IGF-IR/TaqⅠlocus and allele B at CAPN Ⅱ/HhaⅠwere dominant in the studied population which were in Hardy-Weinberg equilibrium at IGF-IR/TaqⅠand CAPN Ⅱ/HhaⅠloci and in Hardy-Weinberg disequilibrium at UCP 3/BglⅠlocus. No statistically significant differences in growth traits were observed between the genotypes at IGF-IR/TaqⅠlocus. There were statistically significant differences between the genotypes at CAPN Ⅱ/HhaⅠlocus for growth traits of six-month individuals and for heart girth and body length of different growth stages (P<0.05 or P<0.01). UCP 3/BglⅠpolymorphism had significant effects on body weight, withers heights and body length of six-month animals, and withers heights, heart girth and body length of twenty-four-month individuals (P<0.05). Individuals with genotypes AB at CAPN Ⅱ/HhaⅠand UCP 3/BglⅠloci had best performance. Therefore, polymorphisms of CAPN Ⅱ/HhaⅠ and UCP 3/BglⅠcan be potential effective markers for early selection in the breeding process of Nanyang cattle.
