Cobia Rachycentron canadum L. reared in low‐salinity water: does dietary sodium chloride affect growth and osmoregulation?

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 ac...

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Bibliographic Details
Published in:Aquaculture research 2014-03, Vol.45 (4), p.728-735
Main Authors: Santos, Renato A, Bianchini, Adalto, Jorge, Marianna B, Romano, Luis A, Sampaio, Luís A, Tesser, Marcelo B
Format: Article
Language:English
Subjects:
cell proliferation
chloride cells
diet
dietary salt
energy
feed conversion
feed intake
fish
gills
hyper-osmoregulation
K+-ATPase
marine fish
mortality
Na+
Na+, K+‐ATPase
osmoregulation
Rachycentron canadum
salinity
sodium
sodium chloride
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Summary: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.
ISSN:1355-557X
1365-2109
DOI:10.1111/are.12017