We studied the phenotypic effects of polymorphisms at the MYF5 gene in a divergent F2 swine population and found that one polymorphism was due to an insertion and another to a deletion. The genotypes of 359 F2 animals were obtained and the Normal/Normal (NN) and Normal/Insertion (NI) genotypes analyzed to determine associations with phenotypic data for performance, carcass and meat quality traits. Significant differences were observed (p < 0.05) between NN and NI animals for drip (NN = 3.14 ± 1.56; NI = 3.69 ± 2.78%), cooking (NN = 32.26 ± 2.41; NI = 33.21 ± 2.31%) and total loss (NN = 34.16 ± 2.63 and NI = 34.97 ± 2.08%). The Deletion marker was not statistically tested. The results indicate that the allelic variant Insertion is associated with a deleterious effect on meat quality traits and should be monitored in marker assisted selection programs.

The PSS genotypes of 596 F2 pigs produced by initial mating of Brazilian commercial sows and native boars were characterized by PCR-RFLP and the pork quality traits were evaluated. Among the 596 pigs studied, 493 (82.7%) were NN and 103 (17.3%) were Nn. There were no differences between NN and Nn pigs in the following pork qualities: pHu (5.71 ± 0.16 vs 5.70 ± 0.11), intramuscular fat (1.55 ± 0.64% vs 1.65 ± 0.67%), shear force (5552 ± 878 g/1.2 cm vs 5507 ± 826 g/1.2 cm), lightness (44.96 ± 2.05 vs 45.01 ± 1.92), redness (0.64 ± 0.60 vs 0.79 ± 0.55), yellowness (6.62 ± 0.56 vs 6.65 ± 0.48), hue (84.28 ± 5.53 vs 83.41 ± 4.85), or chroma (6.68 ± 0.52 vs 6.73 ± 0.52). However, pork from Nn pigs had a significantly (p < 0.05) lower pH45 (6.41 ± 0.27 vs 6.51 ± 0.26) and greater drip (3.92 ± 1.90% vs 3.06 ± 1.60%), cooking (33.29 ± 2.26% vs 32.50 ± 2.54%) and total (35.67 ± 2.48% vs 34.01 ± 2.58%) loss compared to that of NN pigs. These results indicate that, even in divergent crosses, PSS gene carriers produce pork of poorer quality.