Study On The Changes Of Rumen Environment And Blood Biochemical Indexes In Different Velvet Stages Of Tarim Wapiti

This study aimed to investigate the effect of different velvet stages on the rumen environment,apparent digestibility of nutrients,blood biochemical indexes,hormone levels,cellulase activity and microbial population structure in Tarim Wapiti,in order to provide theoretical basis for the efficient use of roughage in velvet stages of the Tarim Wapiti.According to the single factor experiment design,5 male adult Tarim Wapiti were selected as experimental animals.According to the growth of antler,this experiment was divided into 5 treatments:pre-discharge period,pre-make-up stage,peak of velvet,late stage of velvet and the late stage of sawing.The composition of the diet during the whole experimental period was about 20-25 days per period according to the growth rate of the stripping and velvet,and the trial period was 5 days.Under the same feeding model and the composition ratio of the diet,the results are as follows:（1）There was no significant difference in the rumen pH and NH₃-N concentration of Tarim Wapiti（P>0.05）;MCP concentration,acetic acid,propionic acid,butyric acid,valeric acid and total volatile fatty acid（TVFA）concentrations were increase with the increase of feed intake,late stage of velvet was significantly higher than other velvet stages（P<0.05）,and it decreased significantly after entering the late stage of sawing（P<0.05）.The concentrations of isobutyric acid and isovaleric acid was significantly higher than other velvet stages（P<0.05）.（2）The apparent digestibility of CP,OM and ADF of Tarim Wapiti decreased gradually with the increase of feed intake,and all the stages showed significant difference（P<0.05）,The apparent digestibility of DM decreased gradually,while the apparent digestibility of NDF decreased first and then increased.The apparent digestibility of DM and NDF was not significantly different in each velvet stage（P>0.05）.（3）The concentrations of vitamin D,albumin and urea nitrogen in the blood of Tarim Wapiti increased first and then decreased,and were significantly higher in late stage of velvet than other velvet stages（P<0.05）,and significantly decreased at the the late stage of sawing（P<0.05）,returning to the same level as pre-make-up stage.The globulin concentration was significantly higher in the late stage of sawing than other velvet stages（P<0.05）.There was no significant difference among the pre-discharge stage,the pre-make-up stage,late stage of velvet and the peak of velvet（P>0.05）.（4）The concentrations of estradiol,growth hormone and melatonin increased significantly with the increase of feed intake of Tarim Wapiti,and the difference was significant during each velvet period（P<0.05）.The testosterone concentration decreased significantly from the pre-discharge period to the late stage of velvet（P<0.05）,and increased significantly after entering the sawing stage（P<0.05）.There was no significant difference in insulin concentration among the various velvet stages（P>0.05）.（5）The content of rumen xylanase,cellobiase,carboxymethylcellulase and microcrystalline cellulase increased significantly（P<0.05）Tarim wapiti entered the late stage of velvet growth from the pre-discharge period（P<0.05）.The activity of rumen xylanase,cellobiase and microcrystalline cellulase was significantly increased（P<0.05）and decreased significantly in the late stage of sawing（P<0.05）.The activity of carboxymethylcellulase was significantly higher in late stage of velvet and in the late stage of sawing than other velvet stages（P<0.05）.（6）At the phylum level,the Bacteroides,the Firmicutes and proteobacteria were the dominant bacterial community of rumen of the Tarim Wapiti in different velvet stages.Synergistetes was significantly higher than the velvet stage during the pre-discharge（P<0.05）,and there was no significant difference among the pre-discharge stage,peak of velvet and the late stage of sawing（P>0.05）.Except for the Synergistetes flora,the other bacterial communities had no significant difference in each velvet stage（P>0.05）.At the genus level,the dominant microflora in rumen of Tarim wapiti are unidentified Bacteroides,succiniclasticum and methanobrevibacter.Except for the Anaerovibrio flora,the other bacterial communities had no significant difference in each velvet stage（P>0.05）.In summary,the content of MCP,VFA,nutrition degradation rate,and cellulose-degrading enzymes in rumen all increased significantly with the increasing dry matter intake.The content of some hormones in blood significantly affected the digestibility of diet（positively related with estrogen and negatively related with testosterone）.There was no significant change on the structure of ruminal bacteria（except for the Synergistetes and Anaerovibrio）in different velvet stages of the Tarim Wapiti.