Polymorphism of AA-NAT gene and its relationship with litter size of Jining Grey goat of China

The polymorphisms of arylalkylamine-N-acetyltransferase (AA-NAT) gene in high-prolificacy Jining Grey goat, medium-prolificacy Boer goat and low-prolificacy Liaoning Cashmere, Inner Mongolia Cashmere and Angora goats were detected to analyse their relationships with litter size. Primers (P1-P5) were designed to detect the polymorphisms by PCR-SSCP and PCR-RFLP. For P2, AA, AB and BB genotypes were detected. Sequencing revealed one silent mutation (T132C) of AA-NAT gene in BB in comparison to AA. For P3, CC and CD genotypes were detected and sequencing revealed one mutation (C265T) of AA-NAT gene in CD in comparison to CC, and this mutation resulted in an amino acid change of Arg -> Cys (R89C). The Jining Grey does with genotype CD delivered by 0.56 kids (P<0.05) more than those with CC genotype. For P5, EE, EF and FF genotypes were detected and sequencing revealed one mutation (C586T) of AA-NAT gene in FF in comparison to EE. This mutation caused an amino acid change of Arg -> Trp (R196W). For both P2 and P5, the differences in litter size among three genotypes were not significant in Jining Grey goats (P>0.05). These results preliminarily indicate that allele D at the C265T locus of AA-NAT gene is a potential marker in genetic improvement of litter size in goats.