Abstract:

Abstract：The 5′UTR polymorphism of IGF-I gene was detected by PCR-SSCP in 134 cattle。The results showed that there was one single nucleotide mutation (C→T) in the sequences upstream of exon 1，there are two allelomorphic genes and three genotype。The statistics results finding that allele A was higher than others in Charolais and red steppes，allele B was higher than others in Limousin however two allelomorphic genes have identical frequency in Simmental。AB genotype was higher than others in four groups。Charolais、Simmental and Limousin groups keep a Hardy-Weinberg balanced condition but the red steppes was not。Our study settle the molecular biology foundation for the future research about carcass traits in cattle。