Microstructure of longissimus lumborum muscle in pigs of several breeds and its relation to meat quality traits

A total of 190 animals, representing Polish Landrace, Pietrain, Zlotniki Spotted pigs and Pietrain (Polish Large White Polish Landrace) crosses were investigated. Samples of longissimus lumborum muscle were taken for histological tests and frozen in liquid nitrogen. After microscopic preparations were made, they were subjected to histochemical reactions to identify muscle fibre types differing in metabolism, and to determine the percentage of intramuscular fat and glycogen in the analysed muscle. The analysis of longissimus lumborum structure showed that Pietrain pigs had the largest proportion of FTG fibres and the smallest proportion of STO fibres that are the most beneficial in terms of meat quality characteristics. The greatest diameters of all muscle fibre types were in the muscle of Pietrain (Polish Large White Polish Landrace) crosses, which were also found to contain the lowest number of fibres in the muscle cross-section area. The least favourable meat quality traits were shown by Pietrain pigs. Their meat was characterized by considerable acidification 45 minutes postmortem, lightest colour and the least favourable water holding capacity.