Study On Meat Tenderness With Its Micro/Ultrastructure And Molecular Mechanism In Shanzhu And Crossbreds

Tenderness is one of the important apparent characters of good meat quality, it is affected by many factors, especially the genetic. Shanzhu is a local swine with good meat quality in China. It not only has a good amount of meat production but also has a ruddy color, and tests delicate, fragrant and juicy. Shanzhu and its crossbreed swines (DSxS, BSxS, DxS, BxS and DxBS) were chosen in the present study. The micro/ultrastructure of crossbreeds’ skeletal muscle were studied to research the mechanism of skeletal muscle Ca metabolism upper gene (VDR and calpain systerm) regulate the muscle development and tenderness from cells, subcellular and molecular level. To prove that the tenderness quality of Shanzhu could be inheritanced. Studies have shown that:1 Inheritance of Shanzhu meat tenderness apparent qualityShanzhu swine had the ideal tenderness and other good meat indicator. When Shanzhu was hybridized or backcrossed with Berkshire and Duroc, its good tenderness apparent quality could be inherited. On meat quality, Shanzhu swine had a better combining ability with Duroc than Berkshire.2 Relationship between the development of LD and PM with TendernessHistomorphometric study of LD and PM showed that skeletal muscle fibers of shanzhu swine had the highest comprehensive evaluation of each parameter, Followed by DSxS and DxS, and the comprehensive evaluation of BSxS and DxBS was poor. In Shanzhu swine the DMF and MD were smaller, while the SL was longer, so its meat was tender. The histomorphometric parameters of DS×S and DxS (the crossbreds of Shanzhu swine and Duroc) were improved, which also showed the ideal meat quality and tenderness;however the crossbreds of Shanzhu swine and Berkshire were not unsatisfactory, which showed significant thickening of the muscle fibers, IFA reduced, meat tended to be thicke and hard.3 VDR regulate Ca2+ channels/pumps and Ca signal transduction and the relationship between skeletal muscle developmentAfter hybridization, the rising of CaM and the fall of Ca-Mg-ATPase in skeletal muscle cells resulted the significantly increasing of sarcoplasmic [Ca2+];With the mediating of Ca2+ signal, G Protein-Coupled triggered a chain reaction, The synthesis rate was greater than the hydrolysis rate in sarcoplasmic protein, which led to the muscle fiber thickening and tenderness decreased.4 CAPN1 and CAST on sarcoplasmic protein synthesis in skeletal muscle developmentThe VDR showed a low expression in skeletal muscle. CAPN1 and CAST were low expressed in a state of dynamic balance, which led to the synthesis and hydrolysis of sarcoplasmic protein keeping in a low level of dynamic balance. So it could maintain a relatively thin muscle fibers and the ideal tenderness. But after hybridization, the VDR protein was up expressed significantly, accompanied by the up expression of CAST and the down expression of CAPN1, leading to the increase of CAST/CAPN1. Thereby facilitating the sarcoplasmic protein synthesis, it made the muscle fiber thickening and tenderness decreased.