Effects Of Diets Types On Performance,Gastrointestinal Microbiome And Metabolome Of Fattening Lambs

Diet is the most direct and effective measure to control the structure of ruminant gastrointestinal microflora,and digestive tract microflora is the most important factor affecting feed efficiency and animal production performance.Therefore,studying the relationship among the diet,microbial community and host production performance is significant to improve utilization of feed resources and the performance of animal production.The objectives of this study were to evaluate the effects of feeding pelleted total mixed ration(PTMR)and total mixed ration on growth performance,slaughter performance,meat quality,ruminal fermentation characteristics,microbiome and metabolome of fattening lambs.and explore the mechanism of gastrointestinal microflora,metabolites and growth performance,and provide technical support to the breeding of fattening lambs.In this experiment,single factor grouping and control design was adopted to select 100 weaned lambs of the same breed,the same age and healthy condition at the age of 55 days.They were randomly divided into 2 treatments and fed with pelleted TMR diet and TMR with the same nutrient level,respectively.Five groups of sheep in each feed group were used as repeat,ten lambs in each repeat.The whole plant corn silage was used as the source of forage in the experimental diet.The two treatment groups were pelleted TMR(PTMR group,the whole plant silage maize was used for pelleting after secondary grinding)and mixed TMR(WPCD group).The experimental period was 72 days,and the pre-feeding period was 10 days.and the formal feeding period was 62 days.Weighing was carried out at the ages of 65,78,97,113 and 126,and one lambs(5 lambs per treatment)was randomly selected from each column for slaughter at the age of 126.The growth performance of lambs(including body weight,feed intake,average daily gain,feed conversion rate)and slaughtering performance were measured,and then take the rumen fluid and the contents of rumen and cecum for the determination of ruminal volatile fatty acid,gastrointestinal microflora and metabolomics.The test results show that:1.During the whole period,the daily weight gain of PTMR group and WPCD group were 292.88 g/d and 267.88 g/d,respectively,and the feed conversion rate was 4.03 and 4.21,respectively,with significant differences(P<0.05).The net meat rate of the two groups was32.41% and 29.09%,with significant difference(P<0.05),and the slaughter rate was 49.79%and 47.46%,with extremely significant difference(P<0.01).The dripping loss rate of PTMR group was lower than WPCD group,the cooked meat rate was higher than WPCD group,and the tenderness was also better than WPCD group(P<0.05).Therefore,the water rate of PTMR group was higher and the meat quality was better.The content of volatile fatty acids in PTMR group was also higher than WPCD group(P<0.05).According to the results of production performance,the growth performance,slaughter performance,meat quality and ruminal fermentation parameters of PTMR group were better than WPCD group.2.According to the microbiome results of rumen and cecum,at the genes level,the differential microorganisms(P<0.1)with an abundance of more than 0.5% in rumen and were upregulated in PTMR group were Fibrobacteres,Rikenellaceae,Veillonellaceae.These differential microorganisms have a strong rate of digesting nutrients and play an important role in improving production performance.The Spirochaetes,Prevotellaceae and Phascolarctobacterium in cecum were down-regulated in PTMR group,and were negatively correlated with production performance.3.In this study,the significantly different metabolic pathways enriched by the differential metabolites in KEGG were mainly amino acid metabolism.In rumen,the metabolism of tryptophan,histidine,cysteine and methionine,tyrosine metabolism and steroid hormone biosynthesis were significantly up-regulated in PTMR group.And in cecum,the up-regulated differential metabolic pathways in PTMR group were nicotinate and nicotinamide metabolism,cysteine and methionine metabolism,and tyrosine metabolism.In summary: Compared with the WPCD group,PTMR group could promote the colonization of Fibrobacteres,Rikenellaceae,Veillonellaceae in the rumen and other microbial communities in the rumen,and the changes in the microbiome would up regulated the VFA content in rumen fluid and metabolic pathways of amino acids.The increase of the abundance of beneficial microbial community and the up regulated of amino acids and shortchain fatty acids synthesis pathway in PTMR fed fattening lambs may be the internal mechanism of the increase of feed intake,feed efficiency and production performance of fattening lambs.