Effects Of Combinations Of Ammoniated Corn Straw And Alfalfa Meal On Rumen Fermentation And Several Microorganisms In Vitro

Alfalfa meal（AM）is an important forage in ruminant breeding.Due to its high crude protein content and comprehensive nutrition,alfalfa has the name of"King of forage".However,its price is relatively high,which greatly increases the raising cost.Therefore,it is of great significance for ruminant production to seek forage which can replace alfalfa.The nutrition of corn straw treated by fast high-pressure ammoniation was significantly increased,and the price was relatively low.It is also helpful to improve the recovery and utilization of corn straw,to promote green environmental protection.In addition,the regulation mechanism of fast high-pressure ammoniation of corn straw（ACS）on rumen degradation performance of ruminants is not clear,and has not been reported at home and abroad.Based on the above information,this experiment was conducted to study the effect of substitute ammoniated corn straw for alfalfa meal on rumen fermentation parameters and microflora of rumen by gas production technique in vitro.The results are as follows:1.Effects of different combinations of ammoniated corn straw and alfalfa meal on nutrient composition and in vitro dry matter degradation.It was found that the content of dry matter（DM）of alfalfa hay and ammoniated corn straw was smaller after combination of 100:0,80:20,60:40,50:50,40:60,20:80 and 0:100,and the contents of crude protein（CP）,ether extract（EE）and ash（Ash）decreased with the increase of the proportion of ammoniated corn straw.The content of acid detergent fiber（ADF）and neutral detergent fiber（NDF）increased with the increase of the proportion of ammoniated straw.During the whole48h fermentation,with the increasing of the ratio of ammoniated corn straw,the degradation rate of dry matter digestibility in vitro（IVDMD）decreased gradually in each group.At 48 h after fermentation,the IVDMD（48.05%）of AM:ACS（0:100）group was significantly lower than that of the other groups（P<0.05）.2.Effects of different combinations of ammoniated corn straw and alfalfa meal on rumen fermentation parameters and associative effects in vitro.After 48h of fermentation,the accumulated gas production of AM:ACS（20:80）group was higher than that of the other groups.The ammonia nitrogen（NH₃-N）concentration of AM:ACS（20:80）and AM:ACS（0:100）groups was significantly higher than the other groups（P<0.05）.The mycoprotein（MCP）concentration was highest in AM:ACS（20:80）group,and the concentration of acetic acid and volatile fatty acids（VFA）in AM:ACS（20:80）group was the highest（P<0.05）,and every group of acetic acid/propionic acid ratio was more than 3,which indicating that it belonged to the acetic acid fermentation type.The pH during the fermentation ranged from 6.69 to 7.10.The results of multiple factors associative effects index（MFAEI）and single factors associative effects index（SFAEI）for each combination indicated that only the AM20∶ACS80 group showed all the positive associative effects.3.Effects of different combinations of ammoniated corn straw and alfalfa meal on microflora of rumen in vitro.Different proportion combination of alfalfa meal and ammoniated corn straw has significant effect on the percentage of total bacterial 16S rDNA of F.succinogene,R.flave faciens,R.albus,Fungi and Protozo.With the increase of fermentation time,the relative quantity of R.flave faciens and Protozo decreased significantly（P<0.05）,while the relative quantity of F.succinogene,R.albus and Fungi increased significantly（P<0.05）,while the relative quantity of Fibrisolvens did not change significantly.Conclusion:（1）Under the experimental conditions,the content of CP,EE and Ash of alfalfa hay was higher than that of ammoniated corn straw,and the dry matter of ammoniated straw was higher than that of ammoniated straw after the combination of ammoniated straw and alfalfa hay with crude protein content of 10.32%and 16.13%,respectively.The content of ADF and NDF was higher than that of alfalfa hay,and the degradation rate of DM in vitro increased with the increase of alfalfa hay.The rumen fermentation effect of 20%alfalfa hay and 80%ammoniated corn straw was the best and the combination effect was also the best.（2）Under the experimental conditions,the addition of ammoniated corn straw was beneficial to the production of F.succinogene and R.albus,and increased the colonization of Fungi.After 48h fermentation,the relative numbers of R.flave faciens and F.succinogene reached the highest values,0.036%and 0.26%,respectively.