Effects Of Valerate On Rumen Epithelial Cells Gene Expression,rumen Fermentation And Blood Metabolism

The aim of this experiment was to study the effect of valerate on Bovine rumen epithelial cells（BRECs）gene expression,rumen fermentation and blood metabolism.The first experiment studied the effect of valerate on BRECs gene expression,the experiment is divided into three groups:CON,LV and HV,which added with 0,0.5 and 2 mmol/L valerate to rumen epithelial cells,respectively.Each group had three replicates,and the 0 mmol/L add group was the control group.The second and third experiments studied the effects of valerate on rumen fermentation and blood metabolism of dairy cows.Using a 3×3 latin square experimental design,0,28,56 g/d of sodium valerate was added to the basical diet,and the 0 g/d add group was the control group.Three healthy dry Holstein cows weighing（650±25）kg and equipped with permanent rumen fistulas were selected,and conducted a three-stage feeding experiments of 13 days each,including an adjustment period of 10 days and a sampling period of 3 days.The results are as follows:Exp.1 evaluated the mRNA differential genes and differential signaling pathways induced by valerate using transcriptome analysis.The results showed that:（1）787 genes were significantly differentially expressed in CON-vs-LV group and CON-vsHV group.The gene expression of proinflammatory factors,TNF,IL32 and IL34 were significantly up-regulated in the valerate addition group,and the gene expression of chemokines,CXCL2 and CXCL8 were significantly up-regulated,and the gene expression of Solute carrier（SLC）family were significantly up-regulated.（2）The addition of valerate activated Cell adhesion molecules（CAMs）and Mitogen-activated protein kinase（MAPK）signaling pathway.Exp.2 evaluated the effects of valerate on rumen fermentation and microbial community structure in dairy cows.The results showed that:（1）Rumen pH values of the three groups were kept at the range of 6.21-6.59 before and after feeding.There was no significant difference in the pH among groups（P>0.05）.The content of NH3-N increased by feeding and decreased with time sequence,and the values were in the range of 3.23-16.71 mg/dL.Furthermore,the rumen NH3-N content of 28 g/d valerate group was significantly higher than that of 56 g/d valerate group and control group（P=0.03）at 2 h after feeding,however,there was no significant difference between the control group and the valerate group at the other sampling time（P>0.05）.（2）The total volatile fatty acids,acetate,propionate,isobutyrate,butyrate,isovalerate,valerate concentration in control group and valerate addition group showed up and drop after feeding.There was no significant difference in the contents of total volatile fatty acids,acetate,isobutyrate,isovalerate,valerate and the ratio of Ac/Pr among groups（P>0.05）.Rumen propionate content in 28 g/d valerate group was significantly higher than that in 56 g/d valerate group and control group at 2 h after feeding（P=0.03）,isobutyrate in 28 g/d and 56 g/d valerate group was significantly higher than that in control group（P=0.01）,and 28 g/d group showed significantly higher than 56 g/d valerate group（P<0.05）.（3）Different levels of valerate had no significant effect on the digestibility of CP,NDF and ADF（P>0.05）.（4）Different levels of valerate had no significant effect on Chao1,Shannon and Coverage index（P>0.05）.（5）At the phylum level,there was no significant difference in the top 10 bacterial relative abundance among groups（P>0.05）.At the genus level,in the top 10 bacterial relative abundance among groups（P>0.05）.Beside,the relative abundance of Prevotella in 56 g/d valerate group showed a decreasing trend（P=0.06）.Exp.3 compared the effects of valerate levels on blood routine,serum biochemistry,serum metabolism and immune indexes in dairy cows.Different levels of valerate（1）had no significant effect on WBC,RBC,HGB,HCT and PLT（P>0.05）;（2）had no significant effect on ALT,AST,ALP,GGT and LDH（P>0.05）;（3）had no significant effect on TP,ALB,GLO,A/G,CREA,BUN and UA（P>0.05）;（4）had no significant effect on TBIL,GLU,CHO and TG（P>0.05）;on IgA,IgM and IgG（P>0.05）;（5）had no significant effect on SOD and GSH-Px（P>0.05）.However,the KEGG pathway enrichment analysis of differential metabolites by untargeted metabolism analysis of dairy cows based on LC-MS technology,showed that Citrate cycle（TCA cycle）,Caffeine metabolism,Glucagon signaling pathway,Alanine,aspartate and glutamate metabolism were affected by valerate.In conclusion,valerate activated the inflammatory response of rumen epithelial cells in dairy cows.The addition of 28 and 56 g/d valerate in the diet had no effect on rumen carbohydrate fermentation,but affected on protein degradation and amino acid metabolism.