| Carnosine is mainly exists in the brain and skeletal muscle of most vertebrates.It is an endogenous natural dipeptide with significant effects of growth-promoting and antioxidation.It has been applied in pigs and chickens.The aim of this experimentwas to study the effects of carnosine supplementation in diets on fattening performance,fecal microbial diversity and serum metabolome characteristics of sheep,and to explore the possible pathways and reasons for promoting growth.Ninety Dorhan hybridlambs(Dorper ♂× Small Tail Han ♀)with similar weight(30±5kg)at the age of about 3 months were randomly divided into 3 groups,30 lambs in each group: control group without carnosine,group 1 with carnosine 400mg/kg,and group 2 with carnosine 800mg/kg.The pre-trial periodwas 10 days,and the carnosine dosage was gradually added until the test dose The trial period was divided into two stages,30 days for each stage.At the end of the first stage,the weight was weighed and the average daily gain(ADG)was calculated to determine the appropriate addition amount of 400mg/kg.In the second stage,the experimental group was fed with 400mg/kg carnosine.At the end of the experiment,12 sheep were selected in the control group and the experimental group to collect feces and blood samples.The differences of fecal microbiota was analyzed by 16 sr RNA sequencing.Serum metabolites were analyzed by liquid chromatography-tandem mass spectrometry(LC-MS/MS)metabolome technique.The test results are as follows:1.In the first stage of the trial,compared with the control group,the weight gain and ADG of group 1 were significantly increased(P<0.01),and the weight gain and ADG of group 2 were significantly decreased(P<0.05).In the second stage,the weight gain and daily weight gain of the experimental group were significantly higher than those of the control group(P<0.01).2.The effects of dietary carnosine supplementation on sheep fecal microbiota wer e as follows: the results of principal coordinate analysis(PCo A)and similarity analysis(ANOSIM)showed that there were significant differences in microbial composition at phylum and genus levels(P<0.05).At the phylum level,the dominant bacteria in the carnotiin group and the test group were Firmicutes and Bacteroidetes,and there was n o significant difference between the two groups(P>0.05).The abundance of Patesciba cteria in the carnotiin group was significantly lower than that in the control group(P<0.01).At the genus level,the dominant genera of the two groups were UCG-005,noran k＿f＿＿Muribaculaceae and Rikenellaceae＿RC9＿gut＿group,with no significant differen ce(P>0.05).The abundance of Clostridiales＿bacterium＿CHKCI001,Syntrophococcu s and Succiniclasticum in the carnosine group was significantly higher than that in the control group(P<0.05).Escherichia-Shigella and Candidatus＿Saccharimonas were si gnificantly lower than that in the control group(P<0.05).Paludicola was significantly up-regulated in the test group(P<0.05),and was significantly positively correlated wi th Zileuton O-glucuronide,Caryoptosidicacid,4-hydroxy-5-[4-hydroxy-3-(sulfooxy)ph enyl]pentanoic acid(P<0.05).3.The effects of dietary carnosin supplementation on serum metabolites of sheep were as follows: a total of 68 differential metabolites were found between the two groups(VIP > 1,P < 0.05),including GPCho(15:1/19:0)[glycerine phosphoryl choline(15:1/19:0)],GPCho(16:0/22:4)[glycerine phosphoryl choline(16:0/22:4)],PC(16:0/18:2(9z,12z))[phospholipid(16:0/18:2(9Z,12Z))],Proline,Vitamin C,Lgulono-1,4-lactone(L-gulo-γ-lactone)and other metabolites were significantlyincreased in carnosine-added sheep serum(P < 0.05).and phospholipid(16:0/18:2(9Z,12Z)),1-pyrrolin-5-carboxylic acid and other metabolites were significantly decreased(P < 0.05).The differential metabolites were significantly enriched in 7 pathways,including Choline metabolism in cancer,Ascorbate and aldarate metabolism,Pyrimidine metabolism,,Histidine metabolism,Protein digestion and absorption,Lysine degradation and Glycerophospholipid metabolism.In conclusion,400mg/kg carnosine added to the diet can significantly improve the ADG of sheep,which may play a role by affecting the intestinal flora and serum metabolites of sheep. |
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