Published 2006

Read in Norwegian

Publication details

Journal : Aquaculture , vol. 261 , p. 1335–1345 , 2006

Publisher : Elsevier

International Standard Numbers :
Printed : 0044-8486
Electronic : 1873-5622

Publication type : Academic article

Contributors : Bæverfjord, Grete; Refstie, Ståle; Krogedal, Per; Åsgård, Torbjørn Einar

If you have questions about the publication, you may contact Nofima’s Chief Librarian.

Kjetil Aune
Chief Librarian


Regurgitation (belching) of oil is a problem in sea fanned rainbow trout kept in water with fluctuating salinity. This often coincides with abdominal distension syndrome, which is associated with osmoregulatory stress and lipid indigestion. The present study investigated combined effects of water stability in extruded feeds and fluctuating water salinity on feed consumption, growth, nutrient digestibility, gastrointestinal transit, and accumulation of water and oil in the stomach of rainbow trout. Diets were produced with high or low water stability, which were characterised by a novel water stability test. In an initial 84 days growth experiment, each diet was fed to six groups of 772 g trout, of which three tanks were supplied with full-strength seawater, and three tanks were fluctuated between seawater and freshwater (7 h per day during 3 successive days per week). No significant effects were seen, although the feed intake appeared slightly lowered by low dietary water stability at fluctuating salinity. In a second experiment, each diet was fed to four groups of 1 kg trout, of which two tanks were supplied with full-strength seawater, and two tanks were fluctuated between seawater and brackish water (17 parts per thousand 7 h per day daily). Low water stability of the diet resulted in accumulation of oil in the stomach, and this response was worsened when the salinity of the rearing water fluctuated. It also corresponded with reduced lipid digestibility. Consequently, low water stability of the diet caused an oil separation in the stomach that may result in oil-belching in rainbow trout suffering from osmoregulatory stress. (c) 2006 Elsevier B.V. All rights reserved.