Muscle fibre traits as additional selection criteria for muscle growth and meat quality in pigs - results of a simulated selection

To estimate the direct and correlated responses in meatiness and meat quality, simulated selection was applied using one-trait selection and index selection including muscle fibre traits. In a total of 2024 pigs of German Landrace, Large White, Leicoma, and Schwerfurter breeds, carcass composition, meat quality, and fibre characteristics of the M. longissimus lumborum were analysed and genetic parameters were calculated by using REML variance component estimation. Coefficients of heritability ranged from low to moderate (growth traits: h(2) = 0.22-0.32; meat quality traits: h(2) = 0.17-0.27; muscle fibre traits: h(2) = 0.12-0.20). The total fibre number and the frequency of white fibres correlated positively with live weight (r(g) = 0.44 and 0.44, respectively) and with loin muscle area (r(g) = 0.38 and 0.19, respectively) while the relationships to pH value and drip loss were not as close (r(g) = -0.29-0.19). Selection indices were constructed from live weight and muscle area, from pH value and drip loss, and from muscle structure traits. As expected, simulated selection for live weight or loin muscle area lead to direct positive effects but these were associated with negative effects on meat quality traits (selection intensities: SI = 0.1; 0.5). Using selection for an index from loin area and muscle structure (loin muscle area + total fibre number - frequency of white fibres - frequency of giant fibres) the adverse effect on meat quality was minimized (responses in pH value: -0.05; -0.01) or was changed towards desired direction (responses in drip loss: -0.65%; -0.26%). The results show that fibre characteristics of pig muscle can be used as selection criteria for simultaneous improvement of carcass composition and meat quality in pigs by including indices developed from performance and fibre traits.