Study About The Separation, Identification And Control Of Rabbit Diarrhoea Of Pathogenic Antagonists Tu-1 Instead Of Antibiotics

As one of the major diseases endangering rabbitry, rabbit diarrhea is characteri- zeed by high incidence rate, high mortality rate and great losses; moreover, it is difficult to cure. Nowadays, it has become a problem universally concerned by rabbit breeders all over the world. There are many reasons that cause rabbit diarrhea, bacterial diarrhea is one kind of them, and it is mainly caused by pathogenic escherichia coli. The biological prevention & cure means that inhibit fungi with fungi has become a new way to prevent and cure bacterial diarrhea of rabbits.In 125 strains of bacillus isolated from cecum of healthy rabbits, 64 strains which have an inhibiting effect on pathogenic escherichia coli are screened, and Tu-1 has the most significant inhibiting effect on pathogenic escherichia coli.Through morphological observation, physiological and biochemical experiments and 16S rDNA gene sequence analysis for identifying its species, it is confirmed that Tu-1 is Bacillus velezensis.Detect the tolerability of bacterial strains and the survival rate of bacterial strains after taking effect in simulated gastric juice and intestinal juice environment for different time periods through simulating high cholate environment, strong acid environment and high temperature environment during granulation in the body. The experiment results show that, strain Tu-1 has a stronger tolerability under cholate, strong acid, high temperature and artificial gut environment.Spore, which can tolerate high temperature environment, is the best preparation form. Optimize the liquid-state fermentation conditions of Tu-1 strains for spore production, so as to improve its resistance against severe environment, extend the preservation period of preparation and stabilize its activity. Select suitable carbon source, nitrogen source and inorganic salts for strains Tu-1 by single-factor experiment method. Through orthogonal experiment method to determine the optimum fermentation medium and optimum fermentation conditions for spore production of Tu-1 strains. The optimum culture medium of strains Tu-1 is as following: corn meal in 0.5%, yeast powder in 0.5%, KCl in 0.05% and CaCl2 in 0.04%. The optimum fermentation conditions are: fermentation time is 72 hours, bottling volume is 75mL, inoculation amount is 10% and pH value is 6. After optimization, the spore production rate of Tu-1 is improved to 98.33% and the bacterial population is up to 2×109cfu/mL.The experiment probes into bacillus'influence on curing capacity of young rabbits suffering from diarrhea and intestinal micro-ecology balance as a probiotic feed additive. The results show that, the cure rate of Tu-1 for diarrhea of young rabbits is 100%, it can inhibit the growth of harmful bacteria such as escherichia coli and salmonella etc. and it can promote the growth of beneficial bacteria such as lactic acid bacteria and bifidobacterium etc. The research results provide strong theoretical support for bacillus'application in breeding industry especially rabbitry as a probiotic feed additive.