J. Pirhonen et al., Appetite of chinook salmon (Oncorhynchus tshawytscha) naturally infected with bacterial kidney disease, AQUACULTURE, 189(1-2), 2000, pp. 1-10
We evaluated the use of feed restriction to decrease mortality and infectio
n rates in yearling chinook salmon (Oncorhynchus tshawytscha) naturally inf
ected with Renibacterium salmoninarum, the causative agent of bacterial kid
ney disease (BKD). Fish were purposely stressed and then fed either full ra
tion, 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 gr
oups in excess and the amount of BKD p57 antigen in the kidneys was measure
d by enzyme linked immonosorbent assay (ELISA) to assess effects of infecti
on on feeding rates. Only a few individuals in, each treatment died during
the experiment, but the proportion of fish with detectable antigen concentr
ation increased as ration level decreased. Within each treatment, fish with
undetectable concentrations of p57 antigen ate significantly more than fis
h with elevated antigen levels. Exponential regressions were fitted for eac
h ration level describing the decrease of appetite as levels of antigen con
centrations increased. The data indicate that even fish that were quite sic
k as judged from their relatively high antigen concentrations can still fee
d and that previous food shortage can increase the feed intake to some exte
nt in the sick fish. (C) 2000 Elsevier Science B.V. All rights reserved.