Polymorphisms of candidate genes for meat and carcass quality in Belgian pig populations

Polymorphisms described in literature for several candidate genes affecting meat and carcass quality traits were analysed in pigs of pure breeds and hybrid lines used in Belgium. Associations with phenotypic traits were also examined when possible. A total of 92 pigs were screened for a HincII polymorphism in the calpain, large polypeptide L3 (CAPN3) gene, but all tested animals revealed homogenous. A HinfI heart fatty acid-binding protein (H-FABP) gene polymorphism was tested in 74 pigs, of which 51 had known intramuscular fat content. The frequency of the H allele, characterised by an additional HinfI restriction site compared to the h allele, varied between 0.5 and 1 for the different breeds or lines. No animals of the hh genotype were present and no association with the intramuscular fat content was apparent. An AluI polymorphism in the adrenocorticotrope hormone receptor (MC2R) gene and a SacII polymorphism in the uncoupling protein (UCP2) gene were examined in 368 and 392 pigs respectively, with 330 pigs shared. For both genes, one allele was clearly predominant with an overall frequency of 0.90 and 0.94 respectively. A few lines or breeds differed from the overall pattern. There was no association between the frequencies of the MC2R and UCP2 gene polymorphisms. Due to the low frequency of one of the homozygous genotypes for both genes, a possible association with carcass fat thickness could not be properly examined, but the large differences between both homozygous genotypes nevertheless deserve further attention. The MC2R gene polymorphism was also tested on 246 piglets that have died from colibacillosis. Remarkably, the frequencies of the subordinate allele and the corresponding homozygous genotype were much higher in this population compared to the healthy pig population examined.