The Effect Of Muscle Fiber Characteristics And MyHC Gene On Meat Quality Of Sunit Sheep In Different Feeding Conditions

The aim of this study was investigate the correlation of muscle fiber histochemical characteristics, MyHC gene and meat quality from different feeding conditions in longissimus doris muscle, biceps femaral muscle, triceps brachii muscle of Sunit sheep, to reveal the effect of muscle fiber characteristics on meat quality traits, and provide the basic theory for quality control of Sunit sheep.Muscle fiber characteristics of Sunit sheep in different feeding conditions were studied and showed that number proportions of oxidation type fibers were 12.68%, 36.44%,32.04% in longissimus doris muscle, biceps femaral muscle and triceps brachii muscle respectively, all higher than the corresponding part of captive Sunite sheep, but number proportions of glycolysis type fiber were all lower than the corresponding part of captive Sunite sheep. The trend of number proportion of three type muscle fibers from three body parts were type ⅡA<type I<typeⅡB.MyHC gene expression of Sunit sheep in different feeding conditions were studied and showed that MyHCI and MyHCIIA gene expression in triceps brachii muscle of grazing Sunite sheep were significantly higher than the corresponding part of captive Sunite sheep(p<0.05). MyHCIIB gene expression in longissimus doris muscle and biceps femaral muscle were significantly lower than the corresponding part of captive Sunite sheep (p<0.05). The total expression of MyHCI gene and MyHCIIA gene in three body parts of grazing Sunite sheep was higher than the corresponding part of captive Sunite sheep. The SDS-PAGE profile of MyHC subunit was studied and showed that type MyHCI, type MyHCIIa and type MyHCIIx, were separated in longissimus doris of grazing Sunite sheep, but type MyHCI, type MyHCIIa, type MyHCⅡx and type MyHCIIb were separated in captive Sunit sheep and type MyHCI, type MyHCⅡa, type MyHCIIx and type MyHCIIb were separated in biceps femaral muscle of grazing Sunite sheep and captive Sunite sheep and three MyHC subunit were separated in triceps brachii muscle.-There were close connection among muscle fiber characteristics, the relative expression of MyHC gene and meat quality. The diameter of type I muscle fibers and number proportion of type ⅡB muscle fibers were positively correlated with shear force value(p<0.05).The expression of MyHCI gene was negatively correlated with shear force value in three body parts of Sunite sheep, but the expression of MyHCIIb gene and MyHCⅡx gene was positively correlated with shear force value. The expression of MyHCⅡa gene was positively correlated with a* value (p<0.05).