Cobia Rachycentron canadum L. reared in low-salinity water : does dietary sodium chloride affect growth and osmoregulation?
Date
2012
Journal Title
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Volume Title
Publisher
Blackwell Publishing
Abstract
The effects of NaCl supplementation (0.0%, 2.5%, 5.0%, 7.5% and 10.0% dry weight of a basal diet) on growth, gill histological alterations and osmoregulation of juvenile cobia reared in low-salinity water (5 g L−1) were assessed. At the end of the experiment, gills were sampled for Na+, K+-ATPase activity determination and histological evaluation. In all treatments, no mortality was observed. Results showed that dietary NaCl supplementation did not alter growth. At the highest supplementations (7.5% and 10.0%), juvenile cobia showed higher feed intake and feed conversion ratio. Na+, K+-ATPase activity was higher in fish fed the diet without salt supplementation than in those fed with NaCl-supplemented diets. The number of chloride cells significantly increased with increasing dietary salt level, being 2.5-fold higher in fish fed with 10.0% NaCl supplementation (41 cells mm−2) than in those from the non-supplemented fed group (16 cells mm−2). These findings indicate that dietary salt supplementation stimulated chloride cell proliferation paralleled with a reduction in the gill Na+, K+-ATPase activity, suggesting a possible decrease in energy consumption associated with osmoregulation. However, the suggested energy sparing did not have a significant impact on juvenile cobia growth.
Description
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Journal Article (peer-reviewed)
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Text
Keywords
CHLORIDE CELLS, DIETARY SALT, HYPEROSMOREGULATION, MARINE FISH, SALINITY, NA+, K+-ATPASE, OSMOREGULATION, SODIUM-POTASSIUM EXCHANGING ATPASE, DIET, GROWTH, SUPPLEMENTARY FEEDING
Citation
Santos, R.A., Bianchini, A., Jorge, M.B., Romano, L.A., Sampaio, L.A., & Tesser, M.B. (2012). Cobia Rachycentron canadum L. reared in low-salinity water: does dietary sodium chloride affect growth and osmoregulation?. Aquaculture Research, 1-8.doi:10.1111/are.12017