A within-breed comparison of RYR1 pig genotypes for performance, feeding behaviour, and carcass, meat and fat quality traits

Data on 187 DNA-tested purebred Landrace pigs were used to compare heterozygous RYR1 types (Nn) and normal homozygotes (NN) in performance (growth, fat deposition rate and feeding behaviour patterns), and carcass, meat and fat quality traits. From 75 to 165 days of age, live body weight (BW), ultrasonic midback (UMB) and loin (ULB) backfat measurements were recorded. dit ally on the same animal. Individual voluntary feed intake (DFI), number of visits (NVD) and feeding time (FTD) were measured on a daily basis using an automatic feeding system. Polynomial models with random regression coefficients were used to describe BW, UMB, ULB, DFI, N_VD and FTD as a function of age. Carcass, meat and fat quality traits were analysed using a mixed model with the RYR1 genotype as a fixed effect. No significant (p < 0.05) differences were observed between NN and Nn genotypes for growth, feed intake and feed efficiency at any age, but the NN pigs showed higher values for UMB and ULB (0.68 +/- 0.30 mm and 0.88 +/- 0.40 mm, respectively, at 165 days). The Nn pigs had higher predicted carcass lean content (+ 11.1 +/- 3.7 g/kg) and higher proportion of ham in the carcass (+2.9 +/- 1.4 g/kg). However, they showed lower values of pH measurements at 45 min post-mortem (-0.26 +/- 0.05 in M. longissimus dorsi, LD), and higher electrical conductivity at 45 min (+1.03 +/- 0.17 mus in LD) and 24 h post-mortem (+1.63 +/- 0.29 mus in LD). No significant differences were found between genotypes for intramuscular fat in the M. semimembranosus (SM) and for fatty acid profiles in the subcutaneous backfat and in the intramuscular fat of the SM. The results of this study suggest that Nn pigs would attain their maximum growth rate at later stages than the NN without any relevant change in the feeding behaviour pattern. Also they confirm that Nn pigs are leaner, have greater proportion of high-priced cuts in the carcass and are more prone to develop pale, soft and exudative meats. However, no effect on fat quality traits was found.