The Effect Of Corn Stalk Decomposition Bacteria KB On Rumen Fermentation And Production Performance In Dairy Cows

The objective of this study was to screen out and identify a bacterial strain with a higherdecomposition on corn straw from rumen liquid in dairy cows, and its effects on the rumenfermentation and performance in dairy cows. This work was composed of four experiments.Experiment1, the screening of corn stalk decomposition bacteria and optimization enzymeproduction conditions. In order to screen out a purpose bacterial strain with a higherdecomposition on corn straw from rumen liquid, and optimize its enzyme production conditions,firstly the study uesd corn straw as roughage to feed4holstein cow that fitted with permanentrumen fistula lasted20d and promote the growth of purpose bacteria in rumen. Then mixed thegastric juice of4cows for enrichment culture, aimed at rapid propagation of purpose bacteria.Then they were preliminarily screened using Congo red medium plate count method, and thenselected the strain that had a large transparent circle to degrade corn straw by flask shakingfermentation method．Finally get a strain with a highest decomposition on corn straw, it is thepurpose strain. And the enzyme production conditions of the strain was optimized. The resultshows that the optimum conditions for enzyme production as follows: inoculation quantity was8%,NH4NO3as nitrogen source, tween-80concentration is1%.Experiment2, the identification of corn stalk decomposition bacteria. In order to determinethe bacterial genus of purpose bacteria, this experiment adopted the PCR molecular assay methodto proceed16rRNA gene sequencing of purpose bacteria, learned that target bacteria had a total of1500basic group, encoding500amino acids, AT/CG=687/813. Test results showed that the strainthat was screened out in this trial was Alcaligenaceae based on the BLAST homology comparisionresults, the similarity with Kerstersia bacterial genus was99%, with Bordetella bacterial genus was96%., it was named KB bacterial.Experiment3, the effect of corn stalk decomposition bacteria KB on rumen fermentation indairy cows. This experiment was to study the effect of KB bacteria on rumen fermentation in dairycow. Three Holstein cows with similar body weight, parity, milk yield and fitted with permanentrumen fistula. By3×3Latin square design were assigned to3treatments group with differentlevels of sodium sulfate:0cfu/d （control）,0.7×10¹¹cfu/d （treat1） and1.4×10¹¹cfu/d （treat2）. Theexperiment was divided into3periods and each period lasted for18d, including15d pre-experiment and3d experiment. Rumen pH, the number of protozoa, total number of bacteria,the concentrations of ammoniacal nitrogen （NH3-N）, volatile fatty acids （VFA） and bacterial crudeprotein （BCP） were determined in this experiment after feeding KB bacteria. The result showedthat the rumen pH （treat1:6.49; treat2:6.56）, NH3-N（treat1:14.11; treat2:14.64）,VFAconcentrations （treat2:101.76） and acetic acid concentration （treat1:67.38; treat2:68.31）weremore significantly higher than the control （P<0.05）, while the number of protozoa, propionic acid,butyrate, propionate and acetate to propionate ratios were not significantly difference （P>0.05）.Experiment4, the effect of corn stalk decomposition bacteria KB on production performancein dairy cows. This experiment was to study the effect of KB bacteria on the productionperformance in dairy cow. Eighteen Holstein cows with similar body weight, parity and milk yieldwere assigned to3treatments group with different diet0cfu/d （control）,0.7×10¹¹cfu/d （treat1）and1.4×10¹¹cfu/d （treat2）. Each treatment had six repeat.The experiment was lasted for50d,including10d pre-experiment and40d experiment. Milk yield and milk composition weredetermined in this experiment. The result showed that after feeding KB bacteria in the diet for40d,the4%fat corrected milk of the treat1（19.27kg/d） and treat2（21.34kg/d） were significantlyhigher than that of control （19.18kg/d）（P<0.05）, While the milk protein rate（3.54%） and milk fatrate（3.72%） of treat2was significantly different （P<0.05） compared with the control group.Lactose rate and non-fat soild in each treatments was not significant different （P>0.05）.In conclusion, in this experiment the KB bacteria had a efficient decomposition on corn straw,under38.5℃the optimum conditions for enzyme production as follows: inoculation quantity was8%, nitrogen source was NH4NO3, tween-80concentration is1%. The strain was Alcaligenaceaebased on result of BLAST homology comparision, the similarity with Kerstersia bacterial genuswas99%, and with Bordetella bacterial genus was96%. The KB bacteria had certain effect onstabilization rumen environment and could improve production performance of dairy cow.