魚類における感染およびその防御機構に関する研究 Ｉ コイの体表，皮膚，えらならびに腸管における飼育条件別の付着・増殖細菌数

Abstract

To elucidate the mechanisms of bacterial infection and protection in fish, carps were exposed to changes in water temperature under feeding and fasting conditions and the epiphytic and growth counts of bacteria on the body surface, shin, gill and intestinal tract were investigated. In carps under feeding conditions, hematological properties were also investigated. When the water temperature was changed while the carps were under feeding conditions, there were significant decreases in the erythrocyte counts, hemoglobin levels and significant increases in the epiphytic bacterial counts on the skin two weeks after the start of the experiment. After three weeks, the administration of pantethine (100mg/kg, b.w./day) to the carps subjected to changes in water temperature resulted in improved hematological properties and decreased epiphytic bacterial counts on the skin and gill, while, these counts further increased in carps given the conventional feed. There was a negative correlation between the hemoglobin levels and the Aeromonas counts on the gill(|ro|=0.3428[r(22, 0.05)]). When the water temperature was changed for two weeks under fasting conditions, there were significant increases in the epiphytic bacterial counts on the skin and gill and also in the bacterial counts in the intestinal tract. The types of bacteria showing significant increases were Aeromonas and Alcaligenes on the skin, Aeromonas, Alcaligenes and Pseudomonas on the gill and Aeromonas in the intestinal tract.