The Effects And Mechanism Regulation Of Feeding Systems On Lipid Metabolism Of AMPK Pathway And Meat Quality

16 Sunit sheep of 12 months old were raised in pasture(P Group)and captivity(C Group),respectively.The effects of different feeding pattern on the molecular mechanism of AMPK signalling pathway regulating fat metabolism were investigated with the RT-PCR and ELASA kit.The correction of AMPK expression and fat metabolism factors and meat quality were analyzed in order to present the theoretical and data support of improvement of Sunit meat quality.The results showed that:Slaughter rate,net meat rate,intramuscular fat content and triglyceride content of Sunit sheep in the P group were significantly lower than those in the C group(p<0.05).The shearing force of Sunit sheep in the P group was significantly greater than that in the C group(p<0.05),and the tenderness of mutton in the P group was smaller than that in the C group.Saturated fatty acid content of P group was significantly lower than the C group(p<0.05),single unsaturated fatty acid content and the content of alpha linolenic acid,conjugated linoleic acid,eicosapentaenoic acid,docosahexaenoic acid of P group were significantly higher than in C group(p<0.05),volatile flavor substance mainly in flavour benzaldehyde and nonyl aldehyde are characterized by P group had a significantly higher levels of C group(p<0.05).AMPK activity in the P group was significantly higher than that in the C group(p<0.05),which was significantly negatively correlated with the fat content in the muscles of the two groups(p<0.05),and was significantly negatively correlated with the tenderness of the P group(p<0.05).The protein content of AMPK and CPT1 of biceps femoris muscle(BF)were higher in P Group than in C Group,the activity of AMPK protein and the mRNA expression of AMPK were higher in P Group than in C Group(p<0.05).On the other side,the activity of ACC protein and the mRNA expression of ACC were lower in P Group than in C Group(p<0.05).The results suggested that Sunit sheep raised in pasture condition may affect meat quality by activating the signalling pathway of AMPK-ACC-CPT1 to reduce the deposition of fat and tendness.The mRNA expression of SREBP1-c of BF was lower in P Group than in C Group(p<0.05).The mRNA expression of HSL and LPL were higher in P Group than in C Group(p<0.05).On the other side,the mRNA expression of PPAR? showed negatively significant correlated with the content of SFA(p<0.05).The expression levels of specific proteins UCP-1 and Cyto-c in brown fat in the P group were significantly higher than those in the C group(p<0.05).The key gene expression of white fat brown of UCP-1,PGC1 a,ELOVL3 gene expression in P group were greater than the C group,especially in the larger exercise muscles,for example the biceps femoris muscle and arm triceps expressed significant difference(p<0.05).In order to further study the effects and mechanism regulation of feeding systems on lipid metabolism of AMPK pathway and meat quality,simulation of grazing and feeding system,by constructing exercise model of rats adjust fat metabolism and the impact on the fatty acid composition in mechanism.The results showed that the weight of perirenal fat and abdominal posterior wall fat in the exercise group was significantly lower than that in the control group(p<0.05).AMPK activity in the exercise group was greater than that in the control group(p<0.05).There was a significant difference in UCP-1 protein expression in three parts of the exercise group,and the expression was brown fat > subcutaneous fat > intramuscular fat(p<0.05).UCP-1,PGC1-?,CPT1 in the exercise group were significantly greater than those of the control group(p<0.05).The contents of arachidonic acid,DHA and EPA in BAT in the exercise group were significantly higher than those in the exercise group(p<0.05).Exercise can promote browning of white fat and increase PUFA content by AMPK-CPT1-PGC1-UCP-1 pathway.