Abstract：The estrogen receptor (ESR) plays an important role in animal reproduction through binding specifically with estrogen and interacting with estrogen to regulate the expression of related genes of reproductive function, and was studied as a candidate gene for prolificacy in some goat (Capra hircus) breeds. Single nucleotide polymorphisms (SNPs) of exons 1 and 4 of ESR gene were detected in high prolificacy breed (Jining Grey goat), moderate prolificacy breed (Boer goat) and low prolificacy breeds (Inner Mongolia Cashmere and Angora goats) by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP). Results showed that no polymorphism was detected in the amplified region in the four goat breeds tested. The nucleotide sequences of these two fragments were detected and the corresponding amino acid sequences were deduced. The comparison of the fragments of exons 1 and 4 of goat ESR gene with those of human, cattle, pig, horse, sheep, rat, mouse and chicken ESR gene showed that the homologies of the nucleotide sequences and amino acid sequences of the fragments with these eight species were from 51.3% to 97.3% and from 64.5% to 98.3% respectively. Two special variations were found in amino acid sequence of goats, which were 81st (proline insertion) in exon 1 and 4th (D4N) in exon 4. The results indicated that the ESR gene was highly conserved among mammals, and exons 1 and 4 may not be the functional domains that affect the high prolificacy in goats.
