Effect Of Complex Plant Extracts On Rumen Fermentation,Rumen Epithelial Barrier And Rumen Microbiota Of Meat Sheep

The objective of this research is to study the impact of adding complex plant extracts（CPE）on rumen fermentation,rumen epithelial barrier,and microbial flora in meat sheep under high-concentrate feeding conditions.The findings of this study will provide a theoretical foundation for the practical application of CPE in livestock production.The research consists of three main experiments:Experiment 1:Effect of different levels of complex plant extracts on in vitro rumen fermentation parameters in meat sheepThis experiment utilized an in vitro batch culture method to investigate the impact of complex plant extracts（CPE）on rumen fermentation parameters in meat sheep,and to determine the optimal dosage.A single-factor experimental design was employed,comprising of one control group（CON）and four experimental groups,each with three replicates.The control group was cultured with the basal substrate,while the experimental groups were supplemented with CPE at dosages of 20 mg/kg（Group I）,50 mg/kg（Group II）,80 mg/kg（Group III）,and 110 mg/kg（Group IV）,respectively.p H,ammonia nitrogen concentration（NH₃-N）,bacterial crude protein（BCP）content,and gas production were measured at 3,6,9,12,and 24 hours,and the multiple factor and combination effects index（MFAEI）was calculated.The results revealed that the addition of CPE at different dosages significantly reduced NH₃-N concentration（P<0.05）,while increasing BCP content and gas production（P<0.05）.However,there was no significant effect on p H（P>0.05）.MFAEI calculations indicated that the optimal dosage of CPE was 80 mg/kg,which exhibited the most favorable effects.Experiment 2:Effect of compound plant extracts on rumen fermentation and rumen epithelial barrier meat sheep fed high-concentrate dietsIn this experiment,we investigated the effects of compound plant extract（CPE）on rumen fermentation,rumen epithelial barrier,cell apoptosis,and microbial flora in meat sheep fed high-concentrate diets through a feeding trial.Twenty-four Duhan crossbred lambs with similar body condition,weighing 30.37±0.57 kg,were randomly divided into a control group（CON）and an experimental group（CPE）,with 6 replicates in each group and 2 lambs in each replicate.The control group was fed a high-concentrate basal diet,while the experimental group was fed a high-concentrate basal diet supplemented with 80 mg/kg CPE.The pre-trial period was 14 days,and the formal trial period was 60 days.The results showed that the addition of CPE significantly increased the percentage of propionic acid in the rumen（P<0.05）and significantly reduced the concentration of NH₃-N（P<0.05）.Moreover,CPE significantly increased rumen epithelial cell thickness（P<0.05）,and decreased the m RNA expression of interleukin（IL）-1β,IL-12,and tumor necrosis factor-α（TNF-α）in rumen tissue（P<0.05）.Additionally,CPE increased the m RNA expression of occludin and claudin-4 in rumen tissue（P<0.05）,while decreasing the m RNA expression of apoptotic protease activating factor-1（Apaf-1）,cytochrome C（Cyt-C）,caspase-8,caspase-9,caspase-3,caspase-7,and Toll-like receptor 4（TLR4）in rumen tissue（P<0.05）.Experiment 3:Effect of compound plant extracts on the microbiota of meat sheep fed high-concentrate dietsThrough 16s r RNA sequence analysis of rumen microbiota,it was found that in terms of alpha diversity,CPE reduced the Chao1 index and increased the Shannon index.At the phylum level,CPE significantly increased the relative abundance of Bacteroidota and Synergistota（P<0.05）,while significantly decreasing the relative abundance of Acidobacteriota,Chloroflexi,Spirochaetes and Verrucomicrobiota（P<0.05）.At the genus level,CPE significantly increased the relative abundance of Rikenellaceae＿RC9＿gut＿group,Erysipelotrichaceae＿UCG-002,Lachnospiraceae＿NK3A20＿group,Olsenella,[Eubacterium]＿ruminantium＿group,Acetitomaculum,Prevotellaceae＿UCG-004,Christensenellaceae＿R-7＿group,Schwartzia,Sphaerochaeta,Pyramidobacter,and[Eubacterium]＿eligens＿group（P<0.05）in rumen microbiota.LEf Se analysis showed that the CPE group was enriched with more beneficial bacteria.Spearman correlation analysis showed that butyric acid was significantly positively correlated with Megasphaera,Pyramidobacter,Christensenellaceae＿R-7＿group,and Synergistota,and significantly negatively correlated with MND1 and Acidobacteriota.IL-1βm RNA expression in rumen tissue was significantly negatively correlated with Acetitomaculum and Olsenella.Caspase-9 was significantly negatively correlated with Acetitomaculum.Claudin-4 was significantly positively correlated with Christensenellaceae＿R-7＿group.In summary,the findings of this study demonstrate that administration of 80 mg/kg CPE can effectively modulate the rumen microbiota structure,reduce the expression of inflammatory factors and apoptosis in rumen tissue,increase the expression of tight junction proteins,improve rumen fermentation and rumen tissue morphology,and alleviate lamb rumen dysfunction caused by high-concentrate feed.