Study On Effects And Associative Effects Of Bacillus Subtilis And Monensin In Beef Cattle Diet

Bacillus subtilis and monensin are commonly used rumen regulators.They are widely used at home and abroad because they can significantly improve the growth performance of beef cattle and improve the economic benefits of breeding.However,most of the beef cattle farms in the mountainous area of Southern Ningxia do not pay enough attention to this,they are denied in the process of beef,at the same time,some farmers use them in combination due to misunderstandings,which affects the application effects.Therefore,it is of great signific-ance for their scientific utilization to systematically carry out research on the effects and associative effects of Bacillus subtilis and monensin in beef cattle diet.In this study,the Simmental fattening bull was used as the experimental animal,and the combination of in vitro gas production method and feeding test was used to evaluate the effects and their associative effects of supplementing Bacillus subtilis and monensin in the diet on beef cattle through three relatively independent experiments.Experiment 1.Evaluation effects and associative effects of Bacillus subtilis and monensin by in vitro gas production method.In this experiment,three healthy Simmental fattening bulls were selected as rumen juice donor animals,and Bacillus subtilis（BS）and monensin（Mo）were mixed with the basic fermentation substrate at different dosages（0BS+0Mo,0.005%BS+0Mo,0BS+0.002%Mo,0.0025%BS+0.001%Mo,0.0035%BS+0.0006%Mo）to form five fermentation substrates I（Blank control）,II（100BS:0Mo）,III（0BS:100Mo）,IV（50BS:50Mo）,V（70BS:30Mo）to perform in vitro gas production test.The results show:（1）There were no significant difference in GP₃₆（36h cumulative gas production）of each experimental groups（P>0.05）.Compared with group I,GP₃₆ of group II and group III increased by 2.33%and 5.84%,and group IV and V decreased by 12.28%and 11.70%respectively;Compared with group I,IVDMD（dry matter digestibility）of group II and group III increased by 0.08%（0.12%,P>0.05）and 2.80%（3.68%,P<0.05）,and IVDMD of group IV and group V were decreased by 2.55%（3.80%,P<0.05）and 2.40%（3.57%,P<0.05）;Compared with group I,the MCP（Microprotein）content of group II,group III and group V increased by 1.69 mg/d L（48.70%,P<0.05）,0.09 mg/d L（2.59%,P>0.05）and 0.53mg/d L（15.27%,P>0.05）respectively,the MCP content of IV group decreased by 1.53 mg/d L（44.09%,P<0.05）.（2）Except the p H of group III was significantly lower than that of group I by 0.05（0.72%,P<0.05）,there were no significant difference of p H and NH₃-H（ammoniacal nitrogen）between groups（P>0.05）;Compared with the group I,the TVFA（total volatile fatty acids）content of each experimental groups were increased by 5.63 mmol/L（9.07%,P>0.05）,10.08mmol/L（17.18%,P<0.05）,8.18 mmol/L（13.94%,P<0.05）and 9.73 mmol/L（16.58%,P<0.05）;AA/PA（Acetic acid/propionic acid）of each experimental groups were decreased by0.13（3.65%,P>0.05）,0.20（5.62%,P<0.05）,0.17（4.78%,P>0.05）and 0.18（5.06%,P>0.05）respectively compared with group I.（3）The associative effects of GP₃₆,IVDMD,MCP,p H,and NH₃-H of group IV and group V were all"negative associative effects",the associative effects indices were-0.157,-0.058,-0.555,-0.002,-0.050 and-0.146,-0.048,-0.145,-0.006,-0.173,however,the associative effects of TVFA and AA/PA is"positive associative effects",and the associative effects indexs were 0.005,0.001 and 0.042,0.009.Experiment 2.Effects of storage time of mixture of Bacillus subtilis and monensin on gas production and rumen fermentation parameters in vitro.In this experiment,three healthy Simmental fattening bulls were selected as rumen juice donor animals,the BS and Mo mixtures（according to the mixture of 85%BS and 15%Mo）were mixed with the basic fermentation substrates to prepare five fermentation substrates（A,B,C,D,E）after storaged for 0d,7d,14d,21d and 28d used the A single-factor randomised experimental design of storage time to perform in vitro gas production test.The results show:（1）GP₃₆,gas production rate c,The contents of MCP,NH₃-H and TVFA all decreased gradually with the prolongation of the storage time of the mixture of BS and Mo,but the AA/PA increased gradually;GP₃₆,gas production rate c,MCP and NH₃-H contents were significantly negatively correlated with storage time（P<0.05）,and the correlation coefficients r were 0.931,0.949,0.900,and 0.920;The content of TVFA was significantly negatively correlated with storage time（r=0.987,P<0.01）;AA/PA was significantly positively correlated with storage time（r=0.958,P<0.05）.（2）The effects of mixture storage time on MCP content was greater than that on GP₃₆（P<0.05）.Experiment 3.Evaluation effects and associative effects of Bacillus subtilis and monensin by feeding experiment.In the experiment,16 Simmental fattening bulls were selected as experimental animals and randomly divided into 4 groups A,B,C,and D（4 replicates in each group,1 cow in each replicate）,they were fed with basic TMR（blank control）,basic TMR+0.005%BS（100 BS:0Mo）,basic TMR+0.002%Mo（0 BS:100 Mo）,basic TMR+0.0035%BS+0.0006%Mo（70BS:30Mo）in 70 days（prefeeding period is 10d）.The results show:（1）Compared with group A,the DMI（dry matter intake）of group B and group C increased by 0.53 kg/d（5.20%,P>0.05）and 0.92 kg/d（9.03%,P>0.05）respectively,while DMI of group D decreased by 0.18 kg/d（1.77%,P>0.05）;The ADG（average daily gain）of each experimental groups increased by 0.17 kg/d（16.35%,P<0.05）,0.33 kg/d（31.73%,P<0.05）and 0.07 kg/d（6.73%,P>0.05）respectively compared with group A;Compared with group A,the F/G（feed to gain ratio）of each experimental groups decreased by 0.90（9.22%,P>0.05）,1.64（16.80,P<0.05）and 0.72（7.38%,P>0.05）respectively.（2）There were no significant differences in serum biochemical indexes at the beginning of the test,the end of the test and the changes in serum biochemical indexes during the 60-day test period in each group（P>0.05）.（3）The associative effects indices of DMI,ADG and F/G in group D were-0.076,-0.118and-0.047.Based on the above researchs,the following conclusions can be drawn:（1）Adding Bacillus subtilis and monensin to beef cattle diets alone can improve rumen fermentation and improve the growth performance of beef cattle,and the effects of monensin is better than that of Bacillus subtilis under the conditions of this test.（2）Simultaneous addition of Bacillus subtilis and monensin in beef cattle diets will produce a negative associative effects,and the"negative effects"will gradually increase with the storage time.