Effect of Breed on Microstructure and Tenderness of Porcine Semimembranosus Muscle

The objective of the study was to analyse the effect of breed on characteristics of muscle fibres, parameters of intramuscular connective tissue, collagen content, intramuscular fat (IMF) content and tenderness of semimembranosus muscle in pigs. The study was conducted with 16 Złotnicka Spotted (ZS) and 23 Polish Landrace (PL) fattening pigs slaughtered at 210 days of age. The current study showed that compared to the PL breed, the semimembranosus muscle from the local breed of ZS pigs was characterized by a greater percentage of type I fibres, a smaller percentage of type IIB fibres and a smaller diameter of all the three muscle fibre types analysed, while the muscles of PL pigs had significantly thinner endomysium and perimysium and a more compact arrangement of collagen fibres, with a significantly lower percentage of collagen in the muscle and a lower content of total and soluble collagen compared to the muscles of ZS pigs. Furthermore, meat from ZS pigs was more tender (lower shear force value) and had a significantly higher IMF content compared to meat from PL pigs.