Effect Of Transport Stress On The Muscle Fibres Characteristic Of Erhualian And Pietrain Pigs

The objective of this study was to compare the influence of muscle fibre characterstic between Erhualian and Pietrain pigs after transport. The Erhualian pigs are the most prolific pigs in the world, have well-disposed, and exhibit lower growth rate, poorer feed efficiency, and lower lean meat content than conventional Western pig breeds, but sensory quality of their meat is superior and stress-resistant. Pietrain pigs have well lean percentage in the carcass and a lean-to-bone ratio, but stress-susceptible which also produce pale, soft, exudative (PSE) meat. Therefore, this study was designed to investigate postmortem size and distribution of semitendinosus, longissimus dorsi(LD) and psoas muscle fibre type , capillary density of young Erhualian and Pietrain pigs, and whether the response to various levels of sarcomere, glycogen content, lactate dehydrogenase activity, succinate dehydrogenase activity and meat quality characteristics caused by transport.The whole experiment can be divided into two parts:1. Compare of muscle fibre Types in Erhualian and Pietrain PigsMuscle fibre in semitendinosus, longissimus dorsi(LD) and psoas muscle were differentiated by the method of Brooke and Kaiser (1970), which uses the histochemical reactions ATPase, the reaction is highly sensitive for changes in pH and was finely adjusted to allow for clear discrimination between three fibre types, typeⅠ, typeⅡA and typelIB. (1)Erhualian's typeⅠand typeⅡA fibres area in semitendinosus muscle were significantly smaller than Pietrain (P＜0.01), typeⅡB fibres area were remarkablely smaller than Pietrain(P＜0.05).(2)Erhualian's typeⅡB fibres area of in LD were markedly smaller than Pietrain(P＜0.05). (3)Erhualian's typeⅠand typeⅡA fibres area in psoas muscle were markedly smaller than Pietrain(P＜0.05), no significant changes were found in typeⅡB.(4)The proportion of all types were no difference in three muscle. (5) No significant changes were found in ntramuscular connective tissue between breeds, also in semitendinosus, LD and psoas muscle. It demonstrated that the area of all types muscle fibre in Erhualian pigs were smaller than Pietrain corresponds to better meat quality in Erhualian pigs, higher proportion of type I in psoas muscle and lower proportion of intramuscular connective tissue contribute to the tender taste.2. Effect of transport stress on the muscle fibre characteristic of Erhualian and Pietrain pigsThe glycogen content and activities of LDH and SDH in semitendinosus, LD and psoas muscle were using histochemistry method for estimating the muscle energy metabolism capacity. (1)The content of glycogen was no significant changes after transport in three different muscle. (2)The lactate dehydrogenase activity was higher after transport, Erhualian pigs' significantly increased (P＜0.01), Pietrain' markedly increased in LD alter transport (P＜0.05). (3) The succinic dehydrogenase activity was higher alter transport, Erhualian pigs' significantly increased (P＜0.01), Pietrain' markedly elevated in LD alter transport (P＜0.05). These results showed that transport stress could increase the capacity of aerobic and anoxic metabolism, and LD muscle was stress sensitivity, may be it contribute to LD muscle induce bad meat.The length of sarcomares andⅠ-bands were measured on the micrographs of longitudinal sections. The Sarcomere length was no significance in both breeds and treatment. Pietran pigs' BandⅠlength was markedly shorter after transport, but no difference in Erhualian pigs. It indicated that transport stress will influence tenderness and water holding capacity.