|Budget Amount *help
¥2,000,000 (Direct Cost : ¥2,000,000)
Fiscal Year 1995 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1994 : ¥1,500,000 (Direct Cost : ¥1,500,000)
The poultry meats are regarded as a causative food for Clostridium perfringens food poisoning. The organism is also a causal agent of necrotic enteritis of fowl, which is an important bacterial disease next to Colibacillosis. As the control of C.perfringens in the farm are desirable in respect to public health as well as animal hygiene, we studied the risk factors in the fowl management and hygiene of foodstuff.
Carrier rate in the slaughter house : For the examination of C.perfringens, the small intestine and the caecum of 81 birds from 7 farms were sampled in the slaughter house. The positive rates were 73% (50-100%) and 80% (60-100%) , respectively, and the bacterial counts ranged 10^<4.7->10^<6.5>cfu/g.
Carrier rate in the farm : In the examination of 662 birds culled out through the introduction to the forwarding, 10% of caecal contents were positive for C.perfringens. The carrier rate in the 1st week of age was 8%, decreasing to 1% at 4th week, gradually increasing up to 22% at 7th
week, and steeply increased during no-feed-additive period before forwarding. The rates were especially high in the worsening condition, colibacillosis or ascites, etc.
Effect of fasting on carrier rate : Six 14-day-old broilers caged singularly were fasted for a day and restricted 15g/day for successive 2days, and the 3days-cycle were repeated another 2cycle. The experiments were repeated 13 times where the fecal specimens sampled at 17,21,25 days of age, and the contents of small intestine and caecum were examined. In any cases, the positive rates of the fasting group were clearly high (p<0.01) than those on normal feeding group. This result indicates that the stress should provoke the abnormal proliferation of C.perfringens.
Contamination of the foodstuff : The numbers of C.perfringens in the formula feed ranged 200-500MPN/g, and those in the animal materials exceeded 1000MPN/g whereas the plant materials were less than 500MPN/g. A transient fecal shedding was observed in the normal feeding group, however, the organisms was not detected in the caecal contents in the group feeding sterilized feed from a day old.
Toxin production of the isolants : One of 171 isolants from the formula feed (0.6%) , 2 of 161 isolants from the animal materials (1.2%) , and 8 of 114 isolants from the plant materials (7.0%) produced enterotoxin. Contamination of animal raw materials by C.perfringens were more serious than plant raw materials, but the proportion of enterotoxin-producing isolants in the latter were higher than those in the former. Some carrier animals closely related with human life might contaminated the plant raw materials during storage. The median alpha-toxin activity of the 56isolants from the chickens was 0.2AE/ml, but 2 isolants showed activity of 2.0AE/ml or more. Less