Effects Of Clostridium Butyricum On Protein Metabolism And Meat Quality Of Lambs

To investigate the effect of Clostridium butyricum on protein metabolism and meat quality of lambs,18 three-month-old crossbred ewes of Dorper×Small-Tailed Han sheep were randomly allotted to two experimental groups:The control group（CON）was fed a basic diet,and the Clostridium butyricum group（CBG）was supplemented with Clostridium butyricum at 5g/head/d on the basis of the control diet（the viable number of Clostridium butyricum was 5.0×10⁸CFU/g）.The effects of Clostridium butyricum on growth performance,slaughter performance,meat quality and protein metabolism in lambs were investigated and its intrinsic mechanism of action was investigated.The results are as follows:The study on the growth performance and slaughter performance of lambs showed that the final weight,average daily weight gain,carcass weight,carcass height,slaughter rate and muscle mass were significantly higher in the CBG group than in the CON group（P<0.05）,while backfat thickness was significantly lower than in the CON group（P<0.05）.The meat quality of lambs were compared.Compared with the CON group,the a*values of longissimus dorsi muscle and biceps femoris muscle in lambs were significantly higher（P<0.05）,p H_24h,b*values and cooking loss were significantly lower（P<0.05）,and L*values and shear force of biceps femoris were significantly lower（P<0.05）.The taste and volatile flavor components of lambs were investigated using electronic nose,GC-MS and electronic tongue,the results showed that the flavor profiles of the two groups differed,and Clostridium butyricum enriched the aromatic components,hydrides and alkanes in lambs,and increased the intensity of the umami and saltiness of lambs（P<0.05）.Supplementation of Clostridium butyricum to the diet could affect the types and contents of flavor substances in lambs.Compared with the CON group,the relative contents of heptanal,nonanal and decanal in the CBG group were significantly lower（P<0.05）,and the relative contents of 1-octen-3-ol and 1-octanol were significantly higher（P<0.05）.The relative odor activity value（ROAV）in lambs were used to identify key flavor substances,and the results showed that Clostridium butyricum enriched the fatty,mushroom,nutty,onion-like and orange flavors of lambs.The measurement of protein metabolism in lambs showed that the serum TP,ALB content and AKP activity were significantly higher in the CBG group（P<0.05）,and BUN content was significantly lower than that of the CON group（P<0.05）.Compared to the CON group,the crude protein content,muscle fiber cross-sectional area and longissimus dorsi muscle fiber diameter were significantly greater in the CBG group（P<0.05）.In addition,compared with the CON group,the levels of aspartate,serine,glycine,valine,leucine,lysine and histidine in the longissimus dorsi muscle of the CBG group were significantly higher（P<0.05）,the levels of cysteine,leucine and tyrosine in the biceps femoris muscle were significantly higher（P<0.05）,while the levels of serine,lysine and histidine were significantly lower（P<0.05）.The contents of 3-MH in two muscle parts of CBG group were significantly decreased,and the activities of AST,ALT,BCKDH,BCAT,AKP and LDH were significantly increased（P<0.05）.The intrinsic mechanism of Clostridium butyricum affecting protein metabolism in lambs was also evaluated,it was found that Clostridium butyricum significantly up-regulated the m RNA expression of IGF-1,Akt1,m TOR,p70S6K,4EBP1 and the protein expression of Akt in the longissimus dorsi muscle of lambs（P<0.05）,and significantly down-regulated the m RNA expression of Fox O3,MAFbx and the protein expression of Fox O3（P<0.05）.The m RNA expression of IGF-1,Akt1,m TOR and p70S6K were significantly up-regulated（P<0.05）and the m RNA expression of 4EBP1,Fox O3,MAFbx and the protein expression of Fox O3 were significantly down-regulated in the biceps femoris muscle of CBG group（P<0.05）,indicating that Clostridium butyricum may promote protein synthesis in lambs by regulating the Akt signaling pathway.In addition,compared with the CON group,the m RNA expression of Myo G,CAST in the longissimus dorsi muscle was significantly up-regulated in the CBG group（P<0.05）,while the m RNA expression of MSTN in the longissimus dorsi muscle and MSTN,CAPN-1 in the biceps femoris were significantly down-regulated（P<0.05）,indicating that Clostridium butyricum may promote protein deposition and thus affects muscle development in lambs by regulating the Myo G/MSTN and CAPN-1/CAST system.In conclusion,diet supplemented with 5 g Clostridium butyricum can improve the growth performance,slaughter performance and meat quality of lambs,and inhibit protein degradation while promoting the synthesis of skeletal muscle protein.