Distribution of Microorganisms in Animal Feeds and Their Disinfection by Radiation

  • ITO Hitoshi
    Takasaki Radiation Chemistry Research Establishment, Japan Atomic Energy Research Institute
  • KUME Tamikazu
    Takasaki Radiation Chemistry Research Establishment, Japan Atomic Energy Research Institute
  • TAKEHISA Masaaki
    Takasaki Radiation Chemistry Research Establishment, Japan Atomic Energy Research Institute
  • IIZUKA Hiroshi
    Science University of Tokyo

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Other Title
  • 配合飼料中の微生物分布と放射線殺菌効果
  • ハイゴウ シリョウチュウ ノ ビセイブツ ブンプ ト ホウシャセン サッキン

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Abstract

In this study we investigated the distribution of microorganisms in mixed feeds and fish meals, and effect of radiation-inactivation of the microorganisms. The contamination of animal feeds was remarkable, and the number of total counts in mixed feeds in mash for chick and other kind of animals were 5.3×104 to 2.2×106 per gram. The coliforms were counted from 5.l×103 to 6.8×105 per gram which composed mainly of Enterobacter and Klebsiella, whereas Escherichia coli was minor ones. Osmophilic moulds were 9.6×102 to 4.5×105 per gram. Other kind of fungi were 2.l×103 to 4.5×105. In the case of mixed feeds in pellet, total counts were 5.3×103 to 1.0×106, coliforms were 0 to 2.3×103, moulds were 0 to 1.6×103 per gram. The contamination of fish meals was not remarkable, and only the mixed fish meal was contaminated largely with faecal coliforms and other microorganisms. The species of bacteria in total counts in mixed feeds were consisted mainly of Bacillus, Micrococcus, Enterobacter and Klebsiella, whereas Staphylococcus, Pseudomonas, etc. were minor ones. In coliforms counted from Mac-Conkey agar, E. coli was below 1% in many animal feeds. Osmophilic moulds were consisted mainly of species of Aspergillus glaucus group, A. gracilis, A. candidus and a little amount of A. versicolor and Penicillium. Other fungi were consisted mainly of Fusarium, Cladosporium and Rhizopus. In this respect, it seems to be necessary to prevent the damages of feedstuff caused by growth of moulds and insects, and to eliminate pathogens. Osmophilic moulds were radiation-sensitive and eliminated below identification limit by 0.2 Mrad irradiation. Coliforms were more radiation-resistant and they were eliminated by 0.5 to 0.8 Mrad. However, some bacteria such as Pseudomonas marginata, P. radiora and red Micrococcus were survived at doses of 1.0 to 1.5 Mrad.<br> From these results, it could be said that the irradiation at 0.5 Mrad is enough to reduce the total counts below 103 per gram and to eliminate faecal coliforms from mixed feeds, and the dose of more than 0.2 Mrad is necessary to prevent the mould growth during storage.

Journal

  • Nippon Nōgeikagaku Kaishi

    Nippon Nōgeikagaku Kaishi 55 (11), 1081-1087, 1981

    Japan Society for Bioscience, Biotechnology, and Agrochemistry

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