動物性原料飼料에서 salmonella 屬菌의 分離, 生存性 및 初生雛에 대한 實驗的 感染

ISOLATION AND SURVIVAL OF SALMONELLA IN ANIMAL FEED INGEDIENTS AND EXPERIMENTAL INFECTION IN CHICK

This survey was carried out to investigate for contamination rate and survival of Salmonella in animal feed ingredients. Also examined were the Pathogenicity of the isolates in infant chick by experimental inoculation. A total of 260 samples of finished feed and feed ingredients were randomly collected from feed mills in Pusan area from April to September 1986. Salmonella contamination rate in fish meal and bone meal were 5.1% and 1.4%, respectively, but none of the Salmonella was isolated from 92 samples of finished feed. Contamination 1 evels of Salmonella in 6 positive samples of feed ingredients ranged from 21 to 1100 per 100g in calculation by most probable numver(MPN) technique. Of the 11 Salmonella strains identified, 8 were typed as 4 strains of S.derby and each 2 strains of S.enteritidis and S.infantis, and 3 strains were untypable. All of the 11 isolates were susceptible to chloramphenicol and kanamycin, while some of the strains were resistant in order of prevalence to ampicillin. penicillin, streptomycin and tetracyline. Viable counts of S.derby and S.infantis in experimental inoculation were reduced from log 4.4-4.8 to log 2.7-3.3 in animal feed ingredients after storage for 16 weeks at 25℃. In oral inoculation with 10⁵ cut of Salmonella isolates into infant chicks aged 1 to 3 days, S.enteritidis, and S.infantis were found to bedischarged in feces 3 days afterwards, and these two stains and S.derby were detected from 50, 60 and 70% of the chick, repectively, 7 days after inoculation. S.enteritidis, S.derby and S.infantis were recovered respectively from about 60% of contents of small intestine and cecum and 30, 10 and 20% of liver 7 days after inoculation.