Influence of breeding systems on pH and histochemical properties of muscle fibres in porcine M. semimembranosus

The purpose of this study was to investigate pH values, fibre type frequency and histological features of Semimembranosus muscle of 15 pigs subjected to three breeding systems. The A group was raised in a large paddock; the B group animals were raised in a collective pen until they reached a live weight of 120 kg and then in the same paddock as the A group; the C group was raised in a collective pen. Breeding systems had no significant effect on pH values and fibre type frequency. Histopathological changes in muscle fibres and connective tissue were observed in 12 of the animals studied regardless of the group. However, analysis of the incidence of alterations showed a higher frequency of lesions in the B group, followed by the C group.

Except for one case of DFD meat, muscle alterations were not associated with an adverse pH. In addition, regenerating fibres, with strong reactivity for neonatal serum, were observed both in apparently healthy and in pathological muscle samples.