Association of the porcine α-lactalbumin gene to growth, carcass, meat quality and reproductive traits

α-Lactalbumin is one of the two major whey proteins in porcine milk and may be a regulatory factor in milk yield. Pigs from the University of Illinois three generation Meishan x Yorkshire reference family (n=259) were genotyped using a PCR-based test for a polymorphism in the 5′ flanking region of the porcine α-lactalbumin gene. The PCR product was digested with RsaI, allowing variation in restriction fragment lengths to be detected by gel electrophoresis. In the F₂ generation, two alleles (A and B) had a frequency of 72.2% and 27.8%, respectively and three genotypes were present at the frequency of 48.3% AA, 48.0% AB and 3.7% BB. Growth, carcass, meat quality and reproductive data were analyzed for associations with α-lactalbumin genotype. There was an association between the α-lactalbumin genotypes and age at puberty (P<.05) with heterozygous gilts exhibiting first oestrus approximately 2 wk earlier than pigs homozygous for the A allele and more than 4 wk earlier than pigs homozygous for the B allele (AB=142.4 d, SD 9.1; AA=155.5 d, SD 9.0; BB=170.0 d, SD 16.1). Embryo /fetal mortality during the 50 d of gestation was also different among the genotypes (AA=29.2%, SD 4.0; AB=33.9%, SD 4.0; BB=6.9%, SD 8.4; P < .05) and there were trends toward higher post-weaning (second parity) ovulation rates for AA and AB compared with BB animals (15.4 ova, SD 1.31; I6.10 ova, SD 1.30; 11.9 ova, SD 2.01, respectively; P<.10). No significant associations (P>.05) were detected between growth and carcass traits and α-lactalbumin genotype. There was trend for an association with the intramuscular fat content of the longissimus (AA=3.67%, SD .50; AB=3.87%, SD .50; BB=5.68%, SD .99; P<.10). This study has demonstrated possible associations between the porcine α-lactalbumin gene and some economically important traits that require further investigation.