The Effects Of Drying Methods And Duration Of Storage On Nitrogen-Fixing Bacteria And Cellulose Degrading Bacteria In Rumen

In this study, bacteria samples (Nitrogen-fixing bacteria, NFB and Cellulose degrading bacteria CDB) were collected from the rumen of holstein cows. These samples were processed into bacteria powder by either vacuum freeze-drying or indoor temperature-drying, and the dried bacteria were stored for30or90days at a room temperature. The objective of this study was to explore the effects of two kinds of drying methods and effects of different duration of storage on active performance of survival bacteria and survival rate.The isolation and identification of facultative anaerobic NFB and CDB from the rumen:three Holstein cows (three and half years old dry period) with permanent rumen fistula were used to provide rumen fluid. Medium separation for the two types of bacteria was studied, and the predominant strains were gotten by physiological and biochemical experiments. The result showed that2of CDB(C1and C2) and2of NFB(Nland N2) were isolated from rumen fluid of cows and they were all facultative anaerobic bacteria.CDB and NFB combined with each other, and form C1N1、C1N2、C2N1、C2N2, four kinds of groups.C1N1was comprised of1part of NFB and4parts of CDB.As a representative,0cfu/d (control), was added to a rumen fermentation in vitro system at a volume of4×109CUF/L.Each treatment was repeated for three times. Values of pH, NH3-N, gas production, bacterial protein content, NDF and ADF, VFA and dry matter degradation rate were measured after24-hour fermentation.The result showed that CDB and NFB mixed culture in vitro fermentation can help ruminant make better use of fiber feed.CDB and NFB were divided into two parts, a part of which being freeze-dried and another part being dried at room temperature. The solid-state agents were storged at room temperature (5～25℃,March to May) for30days and90days. The survival of strains after being dried and stored were resurrected. Spread plate method was used to test the survival rate. The result showed that the survival rate of indoor temperature-dried bacteria was only about53～77%of that of the freeze-dried bacteria after storage (either30or90days). Freeze-drying method was more beneficial to survival rate. Survival rate of bacteria dried at room temperature was only about9%of freezed-dried after90days storage, but survival bacteria were kept at lever of109. This study showed that the survival rate of the freeze-dried bacteria samples was higher than that of indoor temperature-dried samples.The two kinds of survival bacteria after storage and drying were mixed by ratio of4:1(CDB:NFB).The bacteria compound was added to a rumen fermentation in vitro system at a volume of4×109CUF/L. Parameters of fermentation, digestibility of dry matters, NDF and ADF, VFA, and in vitro gas production were measured after24-hour fermentation. The results showed that different drying methods had no significant effects (P>0.05) on the various fermentation parameters (such as pH value, the contents of NH3-N and bacterial protein), digestibility of dry matters,NDF and ADF, VFA, and in vitro gas production.In summary, in the test of in vitro, the active performance of survival bacteria indoor temperature-dried was the same with vacuum freeze-dried. And adding mixed strains could help ruminant make better use of fiber feed. If this results can be applied to actual production, will be able to accelerate the cellulose-decomposing bacteria and nitrogen-fixing bacteria as Animal Microbial Ecological Agents in ruminant feed at large-scale production.