Study On Effects And Mechanism Of Different Forage Sources Dictating The Productivities Of Fatting Lambs

Alfalfa and oats are both commonly used sources of roughage in the diets of fattening sheep in China,and the different sources of roughage in the diets are important causes of which changing the production performance as well as health parameters of the ruminant,and the fiber composition and the content of different forage grasses also have certain differences,and also are important influencing factors in adjusting the control of the gastrointestinal microbiome,some studies have shown that different fiber substances can lead to gastrointestinal microbial flora has significantly different population characteristics and functions,which can affect the changes in the production performance of the ruminant.It has been initially hypothesized that the difference in fiber content in diets with different forage grasses may be an influential factor in the change of microbial flora,so it is of great scientific value to analyze the process of fiber composition of diets on the regulation of microorganisms in the gastrointestinal tract of the ruminant and thus the change of the production performance.The aim of this study is to investigate the effect of two different forage grasses of diets on the production performance,digestion utilization,gastrointestinal microbiome and metabolome of fattened lamb and the correlation between different health parameters,and to analyze the mechanisms by which different fiber compositions affect the changes in the abundance of beneficial intestinal flora and metabolite concentrations and thus regulate and control the health parameters of fattened lamb.In this experiment,24 3-month-old weaned lambs with similar litter size,uniform body weight and good body condition were divided into two treatment groups: oat group（Oat）and alfalfa group（Alf）,with three replicates of four lambs in each group.The weight and feed intake of the fattened lambs were measured before and at the end of the test period,and after the experimental stage,two lambs in good condition were selected from each replicate and accurately weighed and slaughtered,and a total of 12 lambs were slaughtered in the two treatment groups,and the slaughter data were recorded.The left longest dorsal muscle of each lamb was used to determine the meat quality,the rumen and intestinal tissues were collected to observe the morphological differences of the gastrointestinal tract,the rumen surimi and intestinal contents of each lamb were collected to determine the rumen parameters,microbiome and metabolome,and the digestibility of nutrients,and the results were then correlated between microorganisms and performance indicators,microorganisms and metabolites using the Spearman correlation analysis.The results were analyzed using Pearson’s correlation analysis between microorganisms and performance indicators,microorganisms and metabolites,and the correlation between polysaccharide content and core microbiota.The experimental results showed that:1.The total volatile acid content（mmol/L）of the Alf group was 112.71 and the ratio of acetic acid to propionic acid was 2.47,while the total volatile acid content of the Oat group was 102.36 and the ratio of acetic acid to propionic acid was 3.26.The digestibility and total digestibility of all nutrients in the front part of the digestive tract of the fattening sheep in the Alf group were significantly higher than those in the Oat group.The rumen tissue morphology and intestinal tissue morphology of the Alf group were better than those of the Oat group.2.Analysis of microbial results showed that:at the family and genus level,the Alf group of Lachnospiraceae,Acetitomaculum,Methanobrevibacter,Pseudomonas,Prevotellaceae were significantly upregulated.The relative abundance of these microorganisms also increased the concentration of some metabolites,thus regulating metabolic pathways.3.Analysis of the metabolomic results showed that the relationships between microbial and D-proline,L-glutamate,pyridoxine,phenylalanine,L-histidine,kynurenine and riboflavin metabolites that were positively correlated with productive performance were also positively correlated,and all of these metabolites were upregulated in the Alf group.The metabolic pathways that were significantly different and influential in both groups were D-glutamine and D-glutamate metabolism,glutamate metabolism,tryptophan metabolism,arginine and proline metabolism,vitamin B6 metabolism,histidine metabolism,and tyrosine metabolism.4.The content of soluble fiber components in the two diets differed to some extent.The content of mannose,arabinose,galacturonic acid and glucuronic acid in the soluble fiber components of alfalfa diets was significantly higher than their content in oat polysaccharides,and the content of mannose,arabinose,galacturonic acid and glucuronic acid was positively correlated with the growth of beneficial bacteria in the gastrointestinal tract,which influenced the performance of fattened sheep by regulating the growth and colonization of microorganisms.In conclusion,the difference in soluble fiber composition between the two different forage types was associated with the colonization of beneficial microbial flora,which was an important reason for the improved performance and feed utilization of fattening lamb.Compared with the oat diet,the alfalfa diet promoted the colonization of the rumen and cecum by beneficial microbial flora,up-regulated the synthesis pathways of some important metabolites related to growth and development and intestinal stability,and increased the content of total volatile acids in the rumen fluid,improving the intestinal development barrier,which could better improve the performance and parameters of fattening lamb and make the growth and development of meat sheep tend to be healthy and good.