Effects Of Ob Gene On Litter Size In Swine

The purpose of this paper is to find genetic markers affecting litter size with modern molecular biotechnology, thus to provide some bases for using marker assisted selection(MAS) to develop pig breeds or lines with high reproductive efficiency. PCR-RFLP was used to study the genetic variations of ob gene in swine from 3348 bp to 3816 bp. The association between different genotypes of the ob gene and its resultant litter sizes were evaluated by statistic analysis to test whether or not the ob gene can be as a genetic marker affecting litter size.One hundred and forty-five sows from three breeds, Datong white pig Landrace sow and Large Yorkshire were used to test genotypes of ob gene in each sow by using PCR-RFLP . After cutting the locus by Hinf I there was a genetic variation at 3469 bp of ob gene, so it was divided into three genotypes of AA,AB and BB, in which the frequency of A allele was 0.848 and that of B allele 0.152.The GLM procedure in SPSS software was used to analyze the association between genotypes and litter size born and litter size alive. Factors considered were breeds, parity and ob genotypes. Difference among effects of the factors on litter size were multiple compared by Student-Newman-Keuls (SNK) method. The result showed that polymorphisms of ob gene at 3469 bp presented near significant effecs on litter size born at 95% lebel (p=0.052), but no significant effect of ob gene on litter size alive was found (p>0.05). Effect of BB genotypes was different from that of AA and AB genotypes with the order of BB>AB>AA. So the B allele especially BB homozygous showed higher positive effect on litter size. The results suggested that ob gene might be used as an alternative genetic marker applying in MAS for improvement of litter size in swine at the process of practical breeding.