Effects Of Different Non-structural Carbohydrates Diets Supplied With Yeast Culture On Rumen Fermentation And Humoral Metabolites Of Sheep

This study aimed to evaluate the effects of different Non-structural carbohydrates structure diets supplied with yeast culture(YC)on rumen fermentation and humoral metabolites of sheep based on metabolomics and 16 Sr DNA high-throughput sequencing technology,and reveal the application mechanism of YC and provide a theoretical basis for the application of YC in ruminant nutrition.A total of 16 male small-tailed Han sheep(weight: 45kg±2kg;month age: 8±1)equipped with permanent rumen fistulas were selected following a 2 x 2 randomly complete block design with two NSC structure diets and 2 YC levels.According to the NRC feeding standards,the diets with equal metabolizable energy and protein levels and different composition of non-structural carbohydrates(starch + sugar): high starch and low sugar diet(H,27% + 6%),low starch and high sugar diet(L,22%+11%).There were4 treatment groups in the experiment: H diet(Hc),H diet with YC(2.5 g/kg,Ha),L diet(Lc),and L diet with yeast culture(2.5g/kg,La).All sheep were raised in single cages and fed on time at 7:00 and 19:00 every day.The experiment lasted for 28 days(pre-feeding period was 7 days).Rumen fluid was collected at 0h,2h,4h,6h,8h and12 h after feeding in the morning on day 20,rumen fluid,blood and urine were collected before feeding on day 21.Test 1: Effects of different NSC diets supplied with YC on rumen fermentation.The results of rumen fermentation parameters showed that diets supplied with YC significantly increased the concentration of acetic acid,propionic acid and total acid in the rumen(P<0.05),however,did not significantly decreased the rumen p H and NH3-N concentration(P>0.05).Affected by the NSC diet YC,the concentrations of acetic acid,propionic acid,butyric acid,and total acid in the group L were higher than those in the group H,while the p H and NH3-N concentration were not significantly different between the two groups(P>0.05).In addition,volatile fatty acids in rumen were affected by the interaction between NSC diet and YC after sheep’s feeding(P<0.05).The results of rumen microbial community showed that the relative abundance of Ruminococcaceae＿NK4A214＿group and Christensenellaceae＿R-7＿group increased,while the relative abundance of Rikenellaceae＿RC9＿gut＿group,F082,and Prevotella＿1 decreased when diet supplied with YC.Test 2: Effects of different NSC diets supplied with yeast culture on humoral metabolites of sheepThe metabolite results showed that high-starch and low-starch diet supplied with YC involved in the metabolic pathways of glycolysis and sugar metabolism synthesis,metabolism of glycine,serine,and threonine,Alanine,aspartic acid,glutamate metabolism,arginine,proline metabolism in sheep serum;D-glutamine and D-glutamate metabolism,alanine,aspartic acid and Glutamate metabolism,glycine,serine and threonine metabolism in urine;citric acid cycle,fatty acid biosynthesis,alanine,aspartic acid and glutamate metabolism,D-glutamine and D-glutamate in rumen fluid.The metabolic pathways of amino acid metabolism,glutathione metabolism,arginine biosynthesis,glycine,serine and threonine all played a significant regulatory role(P<0.05).Combining the results of different metabolites involved in the serum,urine and rumen fluid in high starch and the low starch groups,the metabolic pathways were affected by YC,and the pathways were: metabolism of glycine,serine and threonine,alanine and aspartame Acid and glutamate metabolism.In conclusion,NSC diet and YC significantly affected the volatile fatty acids and microbial community in rumen and humoral metabolites,and there was an interaction for volatile fatty acids(NSC × YC)and affected the metabolism and synthesis of a variety of amino acids in the body.Low starch and high sugar diets supplied with YC significantly increased the production of volatile fatty acids,improved the composition of the rumen microbial community,and regulated the metabolism of glycine,serine and threonine,alanine,aspartic acid and gluten in sheep.The above results proved that the use of YC should be scientifically according to the diet in the sheep production.