Abstract：The steroid 21-hydroxylase gene (CYP21) was studied as a candidate gene for the high prolificacy in Jining Grey goats. According to the sequence of bovine CYP21 gene, ten pairs of primers were designed to detect base variation of exons 1~10 of CYP21 gene in goat(Capra hircus) low prolificacy breeds (Angora and Inner Mongolia Cashmere goats), medium prolificacy breed (Boer goat) and high prolificacy breed (Jining Grey goat) by PCR-SSCP and PAGE. Only the products amplified by primer P10 displayed polymorphisms. For primer P10, three genotypes (AA, AB and BB) were detected in Inner Mongolia Cashmere, Boer and Jining Grey goats, and two genotypes (AA and AB) were detected in Angora goats. Sequencing revealed six nucleotide mutations (A2789C, C2791A, G2818A, G2851C, G2852T and G2854A) and one deletion mutation（c.2821_2822delCG）at exon 10 of CYP21 gene in the BB genotype compared with the AA genotype. As a result, nineteen amino acids were changed from the 426th to the 448th. The Jining Grey goats with genotype BB and AB had 0.81 (P<0.05) and 0.47 (P<0.05) kids more than those with genotype AA, and the difference of the litter size between genotypes BB and AB was non-significant (P>0.05). These results preliminarily indicate that allele B of CYP21 gene is a potential DNA marker for improving litter size in goats.
