Characterization of porcine leptin receptor polymorphisms and their association with reproduction and production traits

Fatness in pigs is of prime economic importance due to market incentives for production of lean pork and elevated fatness increasing the feed costs. Leptin (LEP) action, mediated through its specific receptors (LEPR), was reported to be involved in the regulation of fatness via feed intake, energy expenditure, and whole-body energy balance in pigs. In this study, we have designed 17 primer sets based on the human and mouse LEPR sequences and successfully amplified coding regions of 15 porcine LEPR exon fragments by polymerase chain reactions (PCR). Four single nucleotide polymorphisms (SNP) of Intron 2, Exons 2, 6, and 18 were found in Landrace, Yorkshire, and Duroc by mutagenetically separated-PCR (MS-PCR) and PCR-restriction fragment length polymorphisms (PCR-RFLP). Chi-square statistics was used to calculate homogeneity of genotypic frequencies of 4 gene polymorphisms for three breeds of animals. Effects of Intron 2, Exon 2, and Exon 18 polymorphisms on the reproduction trait such as litter sizes of sows were evident (p < 0.05) in Duroc and Yorkshire. There was no (p > 0.05) significant influence on the production trait of average daily gain due to four candidate gene polymorphisms in three porcine breeds. However, effects of Exon 6 and 18 polymorphisms on the production trait of backfat thickness were significant (p < 0.05) in Landrace and Yorkshire, respectively. Effects of Exon 18 polymorphisms on feed efficiency were also evident (p < 0.05) in Duroc.