| Copper and zinc have been widely used in pig breeding as an effective growth promoter.In recent years,in order to improve the production performance of animals,the phenomenon of excessive addition of copper and zinc elements in feed has occurred from time to time.A large amount of data shows that the use of heavy metal elements in feed will significantly increase its accumulation in liver,kidney,muscle and other tissues,and excessive metal elements are excreted with feces,significantly increasing the heavy metal content in the surrounding environment.Studies have shown that excessively high concentrations of metal ions will affect the growth,metabolism and other biological characteristics of microorganisms.In this study,the concentrations of copper and zinc in tracheal mucus of 65 slaughtered pigs and 20 feces were detected,and used to provide a basis for the application concentration of copper and zinc in the subsequent pasteurization experiment of Pasteurella in vitro.On this basis,a strain of Pasteurella capsularis A was selected for subculture in 5 different concentrations of copper and zinc in vitro.The effects of copper and zinc on the biological characteristics and virulence of Capsule A Pasteurella multocida were explored.The research content are divided into the following three parts:1.Random sampling investigated the concentration of copper and zinc in 65 tracheal mucus samples and 20 fecal samples in the pig slaughterhouse in Changsha.Using the method of atomic absorption spectrophotometer,it was determined that the concentration of cu and zn in the feces was higher.The content range is 99.9 ～312.1mg / kg,and the zn content range is 155.3 ～ 475.5mg / kg;in the mucus sample,the average cu content is 6.08 mg / L and the average zn content is 9.59 mg / L.This provides a reference for the design of the concentration of copper and zinc in the environment of pasteurization in vitro.2.Pass a strain of Pasteurella(PMA8-1)under the five culture conditions of high concentration copper,high concentration zinc,low concentration copper,low concentration zinc and no copper zinc ion,it was passaged to 32 generations in vitro.The biological characteristics of the above-mentioned passage strains and primary strains are colony morphology,capsule content and growth curve.A comparison revealed that different concentrations of copper and zinc have no significant effect on the growth rate of Pasteurella,but it has a significant inhibitory effect on bacterial differentiation,positively stimulates the colony size of bacteria,and maintains the capsule content of bacteria,And the above phenomenon has a concentration-dependent trend.3.Compare the pathogenicity of the above-mentioned 32 nd generation subcultured bacteria subcultured in vitro under the conditions of high copper,high zinc and no copper zinc addition and primary bacteria,the results showed that the virulence of Pasteurella decreased after passage,and the virulence of copper and zinc on Pasteurella significantly maintained.In this study,by verifying the effect of copper and zinc ions on some biological characteristics of Pasteurella in vitro,and further verifying its effect on the virulence of Pasteurella,in order to speculate the possible effect of copper and zinc on Pasteurella in animals,and then on The reasonable addition of copper and zinc in feed provides experimental data support,and also paves the way for further research on the effects of metal ions on bacteria. |
PDF Full Text Request