Study On The Compound Microbial Feed Additives

Problems caused by antibiotics abuse have became a serious problems of our aqualcultural industry.It is not noly affecting the quality of the poultry products,but threating to the health of consumers.Anbibiotics abusing induce the environment pollution and distory the banlance of the ecological.Meanwhile,when the antibiotics were excessive intook by livestocks,the beneficial gut microorganism will be killed and more easily infected by different diseases.It is nesserary to search a effive way to controll antibiotics abusing in poultry breeding.In this study,the beneficial microorganisms which extracted from the animial gut system were processed to the compound microbal additives.The microbal additives can improve the immunity of the livestocks,by the way,it can improve the livstock’s metabolism level. The microbal additives haved deemed as an efftive way to instead the antibiotics.This experiment has successfully isolated and identified a strain of Lactobacillus R1 which can tolerate the simulated gastric acid and bile salts from fresh excreta of weaned lamb by using acid and bile salts resistance test and selective cultivation method. Studies on the culture medium and the culture conditions of Lactobacillus were conducted by single factor test, orthogonal optimization experiment, adding bacterial growth factor test and others. At the same time, the optimization of the culture medium and the culture conditions of a strain of Bacillus subtilis preserved in our laboratory and a strain of Saccharomyces cerevisiae were also carried out. The microcapsule of Lactobacillus R1 was embedded. Bacillus subtilis fermentation liquid was prepared into the dried mushroom powder by using the vacuum constant temperature drying method. And the solid state fermentation of Saccharomyces cerevisiae was dry grounded into the dried mushroom powder by using natural air drying method. Finally, the microcapsule of lactobacillus R1, the dried mushroom powder of Bacillus subtilis and Saccharomyces cerevisiae were compounded to product a compound microbial feed additive. This preparation has validated in lamb by animal in vivo experiments and the results were as follow:(1) The growth state of Lactobacillus R1 can reach the best when the initial pH was 6.0, the temperature was 34℃, the inoculum concentration was 4% and static cultured for 12-14 hours. Optimal medium: 0.5% peptone, 2% glucose, 1% of beef extract, yeast extract 0.5%, Twain-80 0.1%, calcium carbonate 0.2%, citric acid 0.5% sodium acetate, phosphate 0.2%, magnesium sulfate 0.02%, manganese sulfate 0.005%. Growth factor ratio: Tomato Juice 2%, potato juice 3%, Carrot juice 6%, vitamin C 0.2%. Live bacteria number can reach 7.41 × 109 CFU/m L in this condition. Lactobacillus R1 microencapsulation rate reached 90.5% with good acid resistance and enteric solubility. The survival rate reached 79.5% at room temperature for 90 days and the number of viable bacteria was 3.2×109 CFU /g.(2) The growth state of Bacillus subtilis can reach the best when the initial pH was 7.0-7.5, the temperature was 35℃, the liquid volume was 30mL/250 mL, the inoculum concentration was 7%, the rotate speed was 200 r/min and cultured for 17 h. Optimal medium: Glucose 3%, yeast extract 1.5%, two and 0.2% sodium hydrogen phosphate, sodium dihydrogen phosphate 0.1%. Biomass of bacteria had reached 7.90×109 CFU/mL. Sawdust addition amount was 15g/25 mL. Spore production rate is close to 95% and the number of viable bacteria was 5.71×1010CFU/g.(3) The growth state of Saccharomyces cerevisiae can reach the best when the rotate speed reached 150 r/min, the temperature was 25℃, the inoculum concentration was 1%, the liquid volume was 25 m L/250 m L and cultured for 20 h. Optimal liquid medium: Brown sugar 5%, yeast extract powder 2%, ammonium sulfate 0.1%, potassium chloride 0.2%. The number of live yeast reached 2.38 ×108 CFU/m L. Bran: molasses meal: = 7: 2: 1 to prepare the solid medium and the material water ratio was 1:0.6 mixed with mineral salt solution. The maximum biomass was 8.73×109 CFU/g when cultured for 60 h, which was 231.8 times higher than that before optimization.(4) Experiment results on live animals showed that: the use of compound microbial additives can significantly improve the lamb daily weight gain, at the same time, reduce the ratio of meat and feed and the incidence of diarrhea in weaned lamb. Diarrhea rate was 26.7% in the control group while the incidence rate was 6% in the experimental group, which decreased by 20.7%. In this study, the more excellent microbial feed additive strain was gained and its fermentation conditions were optimized. The effect of compound microbial additives on the weight gain and disease prevention is remarkable, providing a certain theoretical reference for the actual production.