| Cottonseed meal is a high quality plant protein resource,because it contains anti-nutritional factors such as free gossypol,which limits its application in animal production.In order to improve the utilization rate of cottonseed meal,it is necessary to detoxify cottonseed meal.In this paper,different kinds of microorganisms were selected to ferment cottonseed meal by solid-state fermentation method,and the fermentation effect was evaluated by sensory identification,chemical index analysis and in vitro rumen gas production method,so as to select the most suitable strains for the fermentation of cottonseed meal.This experiment is divided into three parts.Experiment 1:Comparison of solid-state fermentation effects of different strains on cottonseed meal single substrate.In this experiment,nine strains of Yeast 1,Fubon yeast,Raman yeast,Lactic acid bacteria,Bacillus subtilis 10071,Bacillus subtilis10089,Bacillus licheniformis,Aspergillus monascus and Aspergillus niger preserved in our laboratory were used to inoculate cottonseed meal as the substrate（inoculation amount was 10%and water amount was 100%）.Solid state fermentation was carried out in an incubator at a constant temperature of 30℃.Through the determination of free gossypol,nutrients and enzyme activity,the most suitable strain of cottonseed meal fermentation was selected,which provided theoretical reference for its application in production practice.The results showed as follows:1)the change of free gossypol content:Compared with the control group,the detoxification rate of free gossypol was 75.39%（P<0.05）by yeast 1（T1）,69.79%（P<0.05）by yeast Fubon（T2）,and 70.19%（P<0.05）by yeast Raman（T3）,The detoxification rate of Lactobacillus group（T4）was 60.63%（P<0.05）,and that of Bacillus licheniformis group（T5）was 57.13%（P<0.05）,The detoxification rate of Bacillus subtilis group 10071（T6）was 750.20%（P<0.05）,the detoxification rate of Bacillus subtilis group 10089（T7）was 55.49%（P<0.05）,the detoxification rate of Aspergillus niger group（T8）was 64.80%（P<0.05）,The detoxification rate of monascus group（T9）was 60.68%（P<0.05）.2)Changes in nutrients:The changes of protein content were small,and the most obvious ones were Yeast 1,Fubon yeast group,Raman yeast,Lactobacillus and Bacillus licheniformis,which increased by 19.46%,12.22%,11.18%,11.71%and 10.72%respectively.The levels of Bacillus subtilis 10071,Bacillus subtilis 10089,Aspergillus niger and monascus were increased by 10.80%,12.77%,15.83%and 13.62%respectively（P<0.05）.The experiment had no significant effect on the nutrient indices such as fat and dry matter（P>0.05）.3)p H value and viable bacteria number:compared with the control group,the p H value of experimental groups was significantly decreased（P<0.05）,while the viable bacteria number was significantly increased（P<0.05）.4)Changes in enzyme activity:compared with the control group,the activities of acid protease,neutral protease and neutral xylanase in experimental group were significantly increased（P<0.05）.Through this test,it can be found that the 9 strains selected in the test can reduce the content of free gossypol,increase the content of protein and fat,and increase the activities of acid protease,neutral protease and xylanase.Yeast 1 reduced the content of free gossypol in cottonseed meal by 75.39%,and the effect was the most significant.Therefore,yeast can be used for solid fermentation of cottonseed meal in order to achieve the effect of detoxification.Experiment 2:Comparison of solid-state fermentation effects of different strains on mixed substrates of cottonseed meal,corn meal and bran（7:2:1）.In this experiment,mixed cottonseed meal was used as substrate for solid-state fermentation to select the most suitable strain for mixed cottonseed meal fermentation.The results showed as follows:compared with the control group,the detoxification rate of free gossypol in Yeast 1（T1）was 73.69%（P<0.05）,the detoxification rate of Fubon yeast group（T2）was 66.10%（P<0.05）,and the detoxification rate of Saccharomyces ramanensis group（T3）was 68.12%（P<0.05）,The detoxification rate of Lactic acid bacteria group（T4）was 51.44%（P<0.05）,The virus-free rate of Bacillus licheniformis group（T5）was 64.94%（P<0.05）,The virus-free rate of Bacillus subtilis 10071 group（T6）was 48.79%（P<0.05）,The virus-free rate of Bacillus subtilis 10089 group（T7）was 57.01%（P<0.05）,The virus-free rate of Aspergillus niger group（T8）was 61.33%（P<0.05）,The detoxification rate of monascus group（T9）was 62.20%（P<0.05）.2)Changes in nutrients:The protein content of Yeast 1 was increased by 20.95%（P<0.05）,14.85%（P<0.05）,11.38%（P<0.05）,18.97%（P<0.05）and 11.47%（P<0.05）,by Fubon,Monascus,Aspergillus niger,and Raman.Lactobacillus increased by 12.22%（P<0.05）,Bacillus licheniformis increased by 18.70%（P<0.05）,and the other strains had little change.The experiment had no significant effect on the nutrient indices such as fat and dry matter（P>0.05）.3)p H value and viable bacteria number:compared with the control group,the p H value of experimental groups was significantly decreased（P<0.05）,while the viable bacteria number was significantly increased（P<0.05）.4)Changes in enzyme activity:compared with the control group,the activity of acid protease,neutral protease and neutral xylanase in this experiment were significantly increased（P<0.05）.The total amylase activity was significantly decreased（P<0.05）.According to the analysis results,all the 9 strains selected in this experiment can reduce the content of free gossypol in mixed cottonseed meal.The degradation rate of free gossypol by Yeast 1 was the most significant,which reduced the content of free gossypol from 439.65 mg/kg to 115.67 mg/kg,and the detoxification rate was 75.39%.In addition,yeast has the most obvious effect on improving protein.Therefore,it is recommended to use Yeast 1 for solid fermentation of the mixture of cottonseed meal.Experiment 3:Comparison of effects of different microbial solid-state ferme-ntation mode of cottonseed meal and rumen fermentation mode of adding different microorganisms directly.The purpose of this study was to evaluate the effects of direct rumen fermentation and solid-state fermentation of cottonseed meal,and to provide a theoretical basis for microbial treatment of cottonseed meal in production.The results showed as follows:1)compared with the control group,the gas production within 48 h in single cottonseed meal group and mixed cottonseed meal group were significantly increased by microorganism solid-state fermentation cottonseed meal group and direct in vitro rumen addition group（P<0.05）.2)The number of viable bacteria in living bacteria group was significantly increased（P<0.05）.3)Compared with the control group,the NH3-N content in living bacteria group was significantly increased（P<0.05）,and the NH3-N content after solid-state fermentation had no significant effect（P>0.05）.4)Compared with the control group,the contents of methane,ethylene-propionic ratio and gossypol in experimental groups were significantly decreased（P<0.05）,and the reduction effect of living bacteria group was more significant,especially the effect of Yeast 1.5)Compared with the control group,the lactic acid content of all strains except lactic acid bacteria was significantly decreased（P<0.05）.6)Compared with the control group,the in vitro digestibility of protein,neutral detergent fiber and acid detergent fiber in experimental group was significantly increased（P<0.05）.In this experiment,it was found that both the cottonseed meal group and the mixed cottonseed meal group adding living bacteria for rumen fermentation could significantly reduce the content of free gossypol,methane and the ratio of ethyl to propylene.The protein digestibility and the contents of NH3-N,MCP and TVFA were significantly increased,and Yeast 1 had the most significant effect.However,rumen fermentation after solid state fermentation has a low degradation rate of free gossypol,so it can be considered to feed cottonseed meal with yeast directly in animal production.According to the above three tests,the fermentation effect and virus-free rate of Yeast 1 were the best in single cottonseed meal and mixed cottonseed meal.In vitro rumen fermentation with living bacteria was better than that with solid state fermentation,and Yeast 1 had the best fermentation effect.Therefore,in ruminant production,direct feeding with yeast can be considered to eliminate anti-nutritional factors and improve the utilization efficiency of cottonseed meal. |
