Appetite of chinook salmon (Oncorhynchus tshawytscha) naturally infected with bacterial kidney disease
In: Aquaculture. Elsevier: Amsterdam; London; New York; Oxford; Tokyo. ISSN 0044-8486; e-ISSN 1873-5622, more
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| Authors | | Top |
- Pirhonen, J.
- Schreck, C.B.
- Gannam, A.L.
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| Abstract |
We evaluated the use of feed restriction to decrease mortality and infection rates in yearling chinook salmon (Oncorhynchus tshawytscha) naturally infected with Renibacterium salmoninarum, the causative agent of bacterial kidney disease (BKD). Fish were purposely stressed and then fed either full ration, half ration, or fasted. At the termination of the 6-week experiment, feed intake of the fish was evaluated by X-radiography after feeding all groups in excess and the amount of BKD p57 antigen in the kidneys was measured by enzyme linked immonosorbent assay (ELISA) to assess effects of infection on feeding rates. Only a few individuals in each treatment died during the experiment, but the proportion of fish with detectable antigen concentration increased as ration level decreased. Within each treatment, fish with undetectable concentrations of p57 antigen ate significantly more than fish with elevated antigen levels. Exponential regressions were fitted for each ration level describing the decrease of appetite as levels of antigen concentrations increased. The data indicate that even fish that were quite sick as judged from their relatively high antigen concentrations can still feed and that previous food shortage can increase the feed intake to some extent in the sick fish. |
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