Effects Of Phytoecdysteroids (PEDS) On Ruminal Fermentation,Microbial Synthesis And Bacterial Abundance Of Gastrointestins In Ruminants

The effects of phytoecdysteroids (PEDS) on ruminal fermentation, microbial efficiency and bacterial abundance of gastrointestins in ruminants have been evaluated on the basis of in vitro gas production, in vitro continuous culture system and cannulated cattle. This study was conducted with attempt to provided scientific basis for rational use of PEDS in feeding ruminants, controlling greenhouse gas emission and improving microbial protein synthesis.Expt1The purpose of this experiment was to evaluate the effects of different levels of PEDS on ruminal fermentation and gas production using the method of in vitro gas production. The results showed that:1) PEDS didn’t significantly influence96h gas production and ruminal dynamic fermentation parameters (P>0.05). With PEDS level increasing,96h gas production linearly decreased (L; P<0.05);2) CH4proportion in24h presented quadratic variation (Q; P<0.01).1%group showed the highest proportion of CH4and the lowest proportion of CO2.3) In24h, with PEDS level increasing, acetate, butyrate and valerate all presented linear variation (L; P<0.05).4%group showed the lowest molar proportion of acetate (P<0.05), and the highest proportion of butyrate and valerate (P<0.05). In96h,3%and4%PEDS decreased the concentration of total VFA. The molar proportion of isobutyrate in3%and4%group was higher than those in1%and2%treatments (P<0.01). As PEDS level increased, the concentration of ammonia nitrogen linearly decreased (L; P<0.01). The concentration of ammonia nitrogen in PEDS treatments was lower than that in control group (P<0.01).4) Differences among the five treatments in24h and48h DM degradation were not significant. The above results indicated that PEDS inhibited ruminal gas production, increased methane proportion and decreased the concentration of ammonia nitrogen. High level of PEDS significantly influenced the ruminal fermentation parameters.Expt2The study aimed to evaluate the effects of PEDS supplementation on rumen fermentation, nitrogen-assimilation enzyme activities and microbial efficiency using a dual-flow continuous-culture system. The results showed that DM and OM digestibility presented quadratic variation (Q; P<0.01), in which0.5%and1%PEDS significantly increased the digestibility of DM and OM (P<0.05). There was no significant difference in digestibility of ADF and CP among all the treatments (P>0.05), and NDF digestibility in1%group was higher (P=0.06) than others; PEDS didn’t significantly influence the concentration of total VFA (P>0.05), whereas decreased the proportion of acetate and the ratio of acetate to propionate, increased the proportion of butyrate, valerate and isovalerate (P<0.05). Isovalerate and valerate presented quadratic variation (Q; P<0.05), acetate, butyrate and A:P presented linear variation (L; P<0.05); Activities of carboxymethyl cellulose (CMCase), glutamate dehydrogenase (GDH), glutamine synthetase (GS) and alanine dehydrogenase (ADH) were increased quadratically with the addition of PEDS (Q; P<0.05); PEDS linearly decreased the concentrations of ammonia nitrogen, linearly increased the daily production of microbial protein (MCP) and microbial efficiency (P<0.05). It was concluded that PEDS influenced the rumen fermentation, improved the activity of certain metabolism enzymes, and increased the microbial efficiency and production of microbial protein.Expt3The objective of this experiment was to evaluate the effect of dietary supplementation with PEDS on duodenal protein flows and dynamic rumen fermentation in beef cattle. The results showed that after feeding, pH values in PEDS treatments were higher than that in control group, the concentrations of ammonia nitrogen and total VFA in PEDS treatments were lower than those in control group. VFA changed over time, the proportion of acetate, isobutyrate, isovalerate and the ratio of acetate to propionate (A:P) decreased in the beginning and then increased, the proportion of propionate, butyrate and valerate rose at first and went down later. In control group, the proportion of propionate was always the lowest, and except at Oh the ratio of acetate to propionate was higher than that in PEDS groups;1%group increased the duodenal dry matter and protein flows, decreased the protein apparently digested in rumen. The above results indicated that PEDS could increase duodenal protein flows, decrease the decline of pH, decrease total VFA, ammonia nitrogen and A:P, increase the proportion of propionate.Expt4This study was conducted to investigate the potential mechanism concerning PEDS influencing ruminal fermentation using real-time PCR. The results showed that PEDS significantly decreased the population of Ruminococcus flavefaciens (P<0.01), which presented linear variation (L; P<0.01). Addition of PEDS at1percent level increased the population of Butyrivibrio fibrisolvens (P=0.06), Ruminobacter ablus and Fibrobacter succinogenes (P<0.05), and they all presented quadratic variation (Q; P<0.05). The percentage of Methanogens in1%treatment was significantly higher than others (P<0.05), Methanogens presented quadratic variation (Q; P<0.05). The results above indicated that PEDS influenced the bacterial community of ruminal cellulose decomposition bacteria, increased the population of Methanogens. No effects of PEDS on rumen bacteria in responsible for protein and starch degradation.Expt5This study was conducted to determine the population of intestinal functional bacteria using real-time PCR. The results showed that the percentage of Clostridium coccoides in1%treatment was higher than others, and presented quadratic variation (Q; P<0.05). Two percent of PEDS significantly increased the population of Enterobacteriaceae (P<0.01), and Enterobacteriaceae presented linear variation (L; P<0.01). PEDS didn’t influence the proportion of Bacteroides fragilis, Bifidobacterium, Clostridium perfringens, Enterococcus, Escherichia coli and Lactobacilli in gut. The results above indicated that PEDS influenced the population of C. coccoides, increased the proportion of Enterobacteriaceae. No effects of PEDS on gastrointestinal functional bacteria else. The optimal dose of PEDS for animal health was1%.