| The purpose of this study was to investigate the effects of dietary energy and protein levels on growth performance,serum biochemical parameters,slaughter performance,meat quality,rumen microflora,metabonomics,and relationships between rumen microflora and metabolomics in Shanbei White Cashmere Goats(SWCG),which would lay a foundation for the efficient use of energy and protein in feed,and provide a reference for studying the relationship between the rumen microflora and metabolites in the SWCG.Seventy-six goats aged from 8-9 months old were selected and randomly divided into two groups,38 in each group.The metabolic energy of the experimental group was 9.24 MJ/kg,the crude protein content was 9.37%,the metabolic energy of the control group was 8.60 MJ/kg,and the crude protein content was 8.73%.The trial period was 65 days,which the first 10 days for adaptation.At the end of the experiment,6 goats were randomly selected from each group to be slaughtered,slaughter performance indicators and meat quality indicators were measured,and rumen fluid,duodenum and ileum contents were collected.High-throughput sequencing was used to investigate changes in rumen microflora,metabolomics was used to investigate changes in rumen metabolites,and quantitative real-time PCR was used to determine the absolute amount of bacteria in the rumen fluid,duodenum and ileum contents.The results show:(1)During the fattening stage of the SWCG,the crude protein content in the diet increased from 8.73% to 9.37%,and the metabolic energy increased from 8.60 MJ/kg to 9.24 MJ/kg,which could significantly increase the SWCG's average daily gain,slaughter rate,eye muscle area,GR values and crude fat content.There was increasing trend in both the quality of meat and the rate of first class meat.(2)A total of 32 phylum classifications and 309 genus classifications were obtained for the rumen bacteria of SWCG.Bacteroidetes,Firmicutes,and Proteobacteria accounted for the highest levels of categorization.The differences in energy and protein levels designed in this study affected the rumen microflora of SWCGs.The abundance of Bacteroidetes in the test group with higher energy and protein levels was significantly higher than that in the control group(P<0.05).The abundance of Prevotella also increased with the level of dietary energy protein(P<0.05).(3)Based on GC-TOFMS metabolomics,607 metabolites were measured and 24 metabolites were obtained after screening(VIP>1.0;P<0.05).The main metabolic pathways involved including polysaccharide metabolism,lipid metabolism,amino acid metabolism,and pyrimidine metabolism et al.(4)Under the experimental conditions of energy and protein level differences,nutritional levels were significantly(P < 0.05)affected the number of Prevotella in the rumen,duodenum,ileum,and significantly(P <0.05)affected the number of Bacteroidetes in the rumen and duodenum.Bacteroidetes and Prevotella showed a decreasing trendency in the rumen,duodenum and ileum.Changes in rumen bacteria have a strong correlation with metabolites in the rumen,where genus Prevotella was associated with lipid metabolism and pyrimidine metabolism,and Firmicutes at the portal level was associated with polysaccharide metabolism,lipid metabolism,and amino acid metabolism.In summary,the energy and protein levels in the diets significantly affected the rumen microflora and metabolites,and the metabolites had a strong correlation with certain rumen bacteria.The more detailed mapping relationship between rumen bacteria and metabolites obtained in this experiment can serve as a theoretical basis for the subsequent study of the efficiently use of energy and proteins. |
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