Comparison between the three porcine RN genotypes for growth, carcass composition and meat quality traits

A three-step experimental design has been carried out to add evidence about the existence of the RN gene, with two segregating alleles RN- and rn(+), having major effects on meat quality in pigs, to estimate its effects on pr oduction traits and to map the RN locus. In the present article, the experi mental population and sampling procedures are described and discussed, and effects of the three RN genotypes on growth and carcass traits are presente d. The RN genotype had no major effect on growth performance and killing ou t percentage. Variables pertaining to carcass tissue composition showed tha t the RN- allele is associated with leaner carcasses (about 1 s.d, effect w ithout dominance for back fat thickness, 0.5 s.d, effect with dominance for weights of joints), Muscle glycolytic potential (GP) was considerably high er in RN- carriers, with a maximum of a 6.85 s.d. effect for the live longi ssimus muscle GP. Physico-chemical characteristics of meat were also influe nced by the RN genotype in a dominant way, ultimate pH differing by about 2 s.d. between homozygous genotypes and meat colour by about 1 s.d. Technolo gical quality was also affected, with a 1 s.d. decrease in technological yi eld fur RN- carriers. The RN genotype had a more limited effect on eating: quality. On the whole, the identity between the acid meat condition and the RN- allele effect is: clearly demonstrated (higher muscle GP, lower ultima te pH, paler meat and lower protein content). and the unfavourable relation ship between GP and carcass lean to fat ratio is confirmed.