Abstract:

Single nucleotide polymorphisms of exon 4 A8398G of the PRL gene were detected in Chinese Holstein cows by PCR-RFLP. The results showed that the PRL gene digested by RsaⅠ could be divided into two kinds of alleles and three kinds of genotypes. The frequencies of allele A and G are 0.257 and 0.743 respectively.The frequencies of genotype AA, AG and GG are 0.010, 0.497 and 0.493 respectively. Sequencing revealed one single nucleotide mutatioo A→G at 8398 bp of the gene in genotype AA in comparison with genotype GG, and this mutation can not result in an amino acid change. The result of Chi Square test indicated that the frequencies of patterns types of PRL gene genes digested by RsaⅠ can not fit with the Hardy-Weinberg equilibrium in this population(P<0.05). In lactation Ⅱ, the least squares means of protein percentage of this population was higher for genotype GG than for genotype AG (P<0.05). The least squares means of milk yield of this population was higher for genotype AG than for genotype GG (P<0.01). The least squares means of linear score of this population was higher for genotype GG than for genotype AG (P<0.05).

Key words: Chinese Holstein cow; prolactin gene; milk production traits;SNPs; PCR-RFLP