Clearance Of Escherichia Coli And Salmonellosis In A Large Scale Broiler Farm In Shanxi

To understand the purification effect of highly sensitive antibiotics on the vertical transmission of E.coli and Salmonella in breeders.In this study,a double PCR method for avian pathogenic E.coli and Salmonella is established.The E.coli and Salmonella isolated and cultured from eggs in Block A and B of A large-scale broiler breeding farm in Shanxi were detected by double PCR.The serology of pullorum and typhoid are monitored by plate agglutination test,and the hygienic indexes of drinking water and feed of breeders are detected.The paper drug sensitivity test method was used to screen highly sensitive drugs for drug purification in Block A,and Block B was used as the control group.The investigation and analysis are carried out from two aspects of feeding management and biosafety measures.The results showed that:(1)The optimal primer concentration was 0.2 μmol/L for double PCR method of Pathogenic E.coli of chicken and Salmonella.The optimal primer dosage of 0.2 μmol/L for double PCR was determined by optimizing reaction conditions and reaction system The best annealing temperature was 65 ℃;The minimum detection limits of double PCR were 102 CFU/m L for E.coli and 10~4 CFU/m L for Salmonella.The results showed that a specific,sensitive and rapid detection of chicken E.coli and Salmonella double PCR method was successfully established in this experiment.(2)The bacteriological index of drinking water and the microorganism index of feed were detected according to the national standard.The results showed that the total number of bacteria in drinking water was 5.5×10~4 CFU/m L,which was more than 550 times of the standard(≤100 CFU/m L),and the total number of coliform bacteria was 102 MPN/100 m L,which was 10 times of the standard(≤10 MPN/100 m L),indicating that the bacteriological indexes of drinking water were not up to standard.No Salmonella was detected in the feed,the total number of bacteria was 4.5×105 CFU/g(< 2×106 CFU/g)and the total number of mold was 2.8×103 CFU/g(< 4.5×10~4 CFU/g),which indicated that the microbial health indexes of the feed were up to standard.(3)According to the results of the drug susceptibility test,a enrofloxacin medication regimen was implemented on the chicken flocks of Medication group,and the infection rate of E.coli and Salmonella in the breeding eggs of Medication group and Control group was monitored.The results showed that the infection rate of E.coli and Salmonella in Medication group decreased from 13.33 % to 0 % and 6.67 % to0 % on the 5th day after administration.On the 20 th day after treatment,the infection rate of E.coli increased to 3.33 %,and the infection rate of Salmonella remained at 0 %.On the 25 th day after treatment,the infection rate of Salmonella and E.coli increased to 1.67 % and 10% respectively.The overall infection rate of E.coli in Control group increased from 10 % to 21.67 %,and the overall infection rate of Salmonella increased from 3.33 % to 6.67 %.The results showed that the treatment with high sensitivity drugs could block the vertical transmission of E.coli and Salmonella.The efficacy period was 20 d for E.coli and 25 d for Salmonella.(4)The serological antibody positive rates of pullorum and typhoid in Block A chickens decreased from 26.67 % to 1.11 % in the 4th week after Sensitive drug therapy.The positive rate of chickens in Control group increased from 16.67 % to 23.33 %.The results showed that the serological positive rates of pullorum and typhoid fever in chickens were significantly decreased by using hypersensitive drugs.The positive rate of pathogen decreased to 0 % and the positive rate of antibody was as high as 33.33 % after one week.The results showed that the positive rate of pathogen was not consistent with the positive rate of antibody.The results showed that the results of serological and etiological tests should be taken into account in the purification of chicken Salmonella blight,so as to prevent the infection of the whole flock caused by missed detection.In conclusion,the sensitive drugs of enrofloxacin can block the vertical transmission of Escherichia coli and Salmonella in chicken for a period of time,and can significantly reduce the serological antibody positive rates of pullorum and typhoid fever in chicken population.The positive rate of Salmonella pathogen is not consistent with the positive rate of antibody.Serological and etiological detection results should be taken into consideration when cleaning Salmonella epidemic in chicken breeders.