| In this experiment,sixteen lambs of 3-month-old Dorper×Small-tailed Han sheep were randomly divided into control group(C)and Clostridium butyricum group(R),eight in each group,half male and half female.Sheep in the C group were fed with basal diet,and those in the R group were fed with basal diet supplemented with 5 g Clostridium butyricum(5×10~8CFU/g)per day for 3 months.The meat samples of longissimus dorsi mucle and biceps femoris muscle were taken as experimental materials and matured at4°C for 1 d,2 d,3 d,4 d and 5 d.The differences and changes of meat quality,fatty acid composition,fat metabolism related enzyme activity,antioxidant enzyme activity and fat oxidation degree were measured and analyzed.The results were as follows:The effects of dietary Clostridium butyricum on meat quality of lambs during post-mortem aging were studied.Compared with C group,the shear force,b*value and cooking loss rate of longissimus dorsi mucle and biceps femoris muscle in R group were significantly decreased during post-mortem aging(P<0.05).The volatile flavor substances of lambs were detected by electronic nose and headspace solid phase microextraction-Gas Chromatograohy-Mass Spectrometry(GC-MS).Compared with C group,the contents of alkanes,nitrogen oxides,aliphatics and hydrides in the longissimus dorsi muscle of lambs in R group were significantly increased during post-mortem aging(P<0.05).The contents of alkanes,aromatic compounds and aliphatic compounds in biceps femoris muscle were significantly increased(P<0.05).The addition of Clostridium butyricum significantly reduced the relative contents of heptanal,nonanal and octanal in the longissimus dorsi muscle of lambs,and the relative contents of heptanal,decanal and hexanal in the biceps femoris muscle were also significantly reduced(P<0.05).Compared with C group,the addition of Clostridium butyricum significantly increased the contents of aspartic acid,glutamic acid,serine,alanine and glycine in the longissimus dorsi muscle of lambs during post-mortem maturation(P<0.05).At the same time,the contents of isoleucine,aspartic acid,serine,histidine and lysine in biceps femoris muscle were significantly increased(P<0.05).The effects of dietary Clostridium butyricum on fatty acid composition of lambs during post-mortem aging were studied.The results showed that the comparative content of SFA in R group was significantly lower than that in C group,while the comparative content of MUFA and PUFA were significantly higher than those in C group(P<0.05).The comparative content of MUFA in biceps femoris muscle was also significantly increased compared with C group(P<0.05).The effects of dietary supplementation of Clostridium butyricum on the activities of enzymes related to fat metabolism during post-mortem aging of lambs were studied.Compared with C group,the content and activity of p-AMPK and CPT1 in longissimus dorsi muscle and biceps femoris muscle of lambs in R group were significantly decreased,while the content and activity of ACC were significantly increased(P<0.05).The content and activity of PPARγand LPL in the longissimus dorsi muscle of lambs in the R group were significantly increased during post-mortem aging(P<0.05),while the content and activity of ATGL in longissimus dorsi muscle were significantly decreased(P<0.05).The effects of dietary Clostridium butyricum on the antioxidant enzyme activity of lambs during post-mortem aging were studied.,it was found that compared with C group,the T-AOC,GSH-Px and CAT activities of longissimus dorsi muscle and biceps femoris muscle in R group were significantly increased during post-mortem aging(P<0.05).In addition,compared with C group,the addition of Clostridium butyricum to the diet significantly reduced the MDA values of the two parts of lambs during post-mortem aging(P<0.05),It shows that the addition of Clostridium butyricum can delay the oxidation process of lambs.In summary,dietary supplementation of Clostridium butyricum can improve the meat quality and flavor formation of lambs during post-mortem aging by mediating AMPK pathway lipid metabolism. |
