인위 유도 조피볼락(Sebastes schlegeli) 식이성 간장증예에 대한 Streptococcus iniae 공격

Abstract

It is known that diseases usually break out by the correlation among three factors of hosts, pathogens and environments. Disease control has been done on pathogen- and environment-oriented basis so far. This traditional control measure doesn’t seem to be successful because of constant outbreaks of same diseases and stubborn high mortality annually. Most of fish diseases are usually infectious by opportunistic pathogens which their infections depend on immunity of host. This study is composed of histopathological and hematological evaluation on rockfish that was different in amount of supplying feed for 5 weeks. Feeding about 1% of body weight was done to control, whereas 5% of body weight was supplied to overfeeding group. A health evaluation was carried out by light microscopical examination of liver that is known as an index organ of nutritional and physiological state. Hypertrophy and fatty change were histologically recorded as the abnormal structures of liver. Histological parameters including hepatosomatic index (HSI), hepatohypertrophic index (HHI) and liver reaction index (LRI), and hematological parameters of hematocrit (Ht) and hemoglobin (Hb), total protein (TP), GOT and GPT were checked. Significant differences in hematological parameters were not found between hypertrophy and fatty change from 0 till 5th week. Overfeeding group was significantly higher than control group in LRI values at 5th week. Obvious correlation between liver health of host and S.iniae challenge was found. Individuals with the higher LRI value were more rapidly dead by the infection. From these results, it was suggested that the state of liver health is very important in acquisition of susceptibility of pathogen in fish.