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Gastrointestinal responses of rainbow trout to dry pellet and low‐fat herring diets
Author(s) -
Ruohonen K.,
Grove D. J.
Publication year - 1996
Publication title -
journal of fish biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.672
H-Index - 115
eISSN - 1095-8649
pISSN - 0022-1112
DOI - 10.1111/j.1095-8649.1996.tb00045.x
Subject(s) - biology , rainbow trout , herring , zoology , stomach , dry matter , trout , catfish , pellet , meal , fishery , food science , fish <actinopterygii> , ecology , biochemistry
Long‐term voluntary‐feeding experiments were carried out on farmed, 2‐year‐old rainbow trout offered a commercial dry feed, or chopped low‐fat Baltic herring. Despite large differences in dietary water, protein and lipid content, the trout adjusted their intake to consume similar amounts of dry matter. After an 18‐week trial, the stomach volumes of the herring‐fed trout were significantly larger (30–35%) than those fed on the dry diet. Greatest differences were observed when fish were fed one meal per day; increasing the number of daily feeding opportunities reduced these expected stomach volumes on each diet by 15–20%. The relative increase in stomach volume was shown to be due to growth of the cardiac stomach region (corpus) rather than the pyloric region, and not to muscle relaxation; the change was completed within 10 weeks. Data were collected in a separate study to investigate stomach size in fish (age 0+, 1+, 2+) of similar genetic backgrounds which had been grown using dry pelleted diets. Despite considerable variation between populations, stomach volume to body weight relationship was allometric ( S = a W b ) with the exponent in the range of 0.3–0.4.