Effects Of Simultaneous Release Of Dietary Energy And Nitrogen On Rumen Fermentation And Nitrogen Metabolism Of Tarim Wapiti

The purpose of this study was to study the effects of simultaneous release of dietary energy and nitrogen on rumen environment and microbial diversity of Tarim Wapiti.The rumen effective degradation rate of common feed of Tarim Wapiti was determined by nylon bag test.The optimum ratio of energy to nitrogen for protein synthesis of rumen microorganisms of Tarim Wapiti was determined by in vitro gas production method.The changes of rumen environment and microbial diversity of different nitrogen release synchronism were measured by collecting rumen fluid.Three parts were completed in this study,the specific contents were as follows:Experiment 1:Study on the dynamic degradation of nitrogen and organic compounds in the rumen of Tarim WapitiThe purpose of this experiment was to determine the effective degradation rate of rumen in the common feed of Tarim Wapiti.Five female Tarim Wapiti with permanent rumen fistula were selected in the experiment,which were in good health condition,（150.0±5.0）kg body weight,and kept in a single cage in a metabolic cage.At 9 o’clock in the morning and 7o’clock in the evening,they were fed twice in the same amount.After 15 days of prefeeding period,nylon bags were placed.Cottonseed hell,reed,poplar leaf,alfalfa,bran,DDGS,corn protein powder,soybean meal were determined respectively.The rumen effective degradation rates of 10 kinds of corn feed,such as DM,CP,OM,NDF and ADF.The results showed as follows:1)The k values of representative energy feed bran,protein feed,soybean meal and roughage cottonseed hull were 3.69%/h,3.67%/h and 3.61%/h.2)The effective degradation rates of cottonseed hell,reed,poplar leave,alfalfa,bran,corn protein powder,soybean meal,cottonseed meal,DDGS and corn DM were among 15.51%-56.75%;the effective degradation rate of CP was in 26.67%-78.99%;the effective degradation rate of OM was between29.97%-77.60%;the effective degradation rate of NDF was between 24.48%-64.83%;the effective degradation rate of ADF was between 33.69%-68.11%.The data obtained in this experiment provide basic data for the subsequent calculation of degradable nitrogen/digestible organic matter（RDN/DOM）,and provide theoretical support for setting up different gradient RDN/DOM diets.Experiment 2:Evaluation of suitable energy nitrogen ratio of Tarim Wapiti by gas production in vitro.In this experiment,a total of 8 different gradients of RDN/DOM（g/kg）ratios of 15,17,19,21,23,25,27 and 29 were used as fermentation substrates,in vitro gas test is rumen pH value,concentration of NH₃-N,contents of VFA,MCP,determine the final appropriate to nitrogen ratio.The results showed as follows:When the RDN/DOM ratio was 23,the concentration of NH₃-N in the culture medium was the lowest,the content of TVFA was the highest,the value of acetic acid/propionic acid was the highest,and the MCP synthesis was the highest.Therefore,it is considered that the optimum nitrogen ratio（RDN/DOM）of Tarim Wapiti is 23,which provides a basis for the calculation of the nitrogen release synchronization index（SI）.Experiment 3:Effects of SI on rumen enviroment index,dietary digestibility and biodiversity of rumen in Tarim WapitiThe purpose of this study was to study the SI on rumen environmental index,dietary digestibility and microbial diversity in Tarim Wapiti.A 5×5 Latin square design was used to study the effects of nitrogen release synchronicity index on rumen environment,dietary digestibility and microbial diversity in Tarim Wapiti.Five grads diets with SI values of 0.57,0.66,0.74,0.82,0.90 were selected.Five female Tarim Wapiti with permanent rumen fistula were selected with good health and similar body weight（150.0±5.0）kg.The microbial diversity in rumen was analyzed by measuring the pH value of rumen,the concentration of VFA and MCP,the digestibility of CP and OM,the digestibility of NDF and ADF,and the analysis of microbial diversity in rumen by high throughput sequencing.The results showed:1)There was no significant difference in the pH value and NH₃-N content of the rumen in the Tarim Wapiti.The MCP content in the SI0.90 group was significantly higher than that of the other four groups,and the higher the SI value,the higher the MCP content was.2)There was no significant difference in the influence of different SI on the apparent digestibility of the Tarim Wapiti,and there was no significant difference in the effects of the protein degrading bacteria,such as Fibrobacter succinogenes,Ruminococcus flavefaciens,Ruminococcus albus,Ruminobacter amylophilus,Butyrivibrio fibrisolvens,Prevotella ruminicola.This shows that the Tarim Wapiti,which has long been adapted to ecological stress,has strong digestive characteristics for different diets.In conclusion,the optimal energy and nitrogen ratio of rumen MCP synthesis in Tarim Wapiti was 23 gRDN/kgDOM,and the effects of different SI values on rumen environment,apparent digestibility and microbial diversity were not significant.It can be seen that the Tarim Wapiti,which has long adapted to ecological stress,has a strong digestive characteristic for different diets,and the adaptation mechanism needs to be further studied.