饥饿对牦牛肌肉脂肪含量及脂肪分解代谢的影响OA

The Maiwa yak were used in this study to explore the changes in intramuscular fat content,lipolysis metabolites,hormones,and enzymes in yaks under starvation conditions.Eight healthy,well-developed,three-year-old Maiwa yaks with similar body weights(110.3±5.85 kg)were selected.A paired design was employed,where yaks with adjacent weights were paired,and one yak from each pair was randomly assigned to either the experimental or control group,with four yaks per group.The control group was slaughtered and sampled on day 1 of the trial.The experimental group underwent starvation treatment,with blood collected from the jugular vein on days 1,3,5,7,and 9.Serum was separated by centrifugation,and the yaks were slaughtered and sampled after blood collection on day 9.The results showed that starvation led to a significant reduction in live weight and carcass weight(P<0.05).After starvation,the intramuscular fat content in the biceps femoris and semitendinosus decreased extremely significantly(P<0.01),while no significant changes were observed in the psoas major,longissimus dorsi,or shank meat(P>0.05).Short-term starvation caused a significant decrease in blood glucose concentration(P<0.05),but as starvation duration extended,the change in blood glucose concentration was not significant(P>0.05).Serum triglycerides and non-esterified fatty acids increased significantly with prolonged starvation(P<0.05),whereas the intermediate products of fat metabolism—β-hydroxybutyrate,acetoacetate,and oxaloacetate—decreased significantly(P<0.05).Serum glucagon and norepinephrine levels increased significantly with prolonged starvation(P<0.05),while insulin decreased significantly(P<0.05).The key lipolytic enzymes in the serum of starved yaks,hormone-sensitive lipase and adipose triglyceride lipase,increased significantly(P<0.05)and peaked on the third day of starvation.These results indicate that starvation reduces the live weight and carcass weight of yaks,regulates hormone secretion in response to blood glucose concentration,increases the levels of key lipolytic enzymes,promotes the breakdown of intramuscular fat,and reduces intramuscular fat content.Additionally,the mobilization of skeletal muscle fat in yaks exhibits spatial heterogeneity.