effects of early nutrition
and of finishing diets on energy metabolisM and body stores of rainbow trout
F.
Médale, S. Gutieres
The
aim of the experiment was to investigate the effects of first feeding
composition on energy metabolism in relation with growth and the potential
consequences on nutrient utilisation in later stages. Rainbow trout fry were
fed isonitrogenous (60% crude protein) diets containing either 7 or 20% fat
from the first feeding onwards for 5 months. The fat-rich diet enhanced
growth and body fat content of fish but the increase in whole body fat was
greater than the increase in weight. Activities of enzymes involved in
energy metabolism (carnitine palmitoyl transferase I, citrate synthase,
isocitrate deshydrogenase and cytochrome oxidase) were slightly affected by
the dietary treatments. Fish were then all fed a commercial diet for 5
months before being challenged with one of two diets (45% crude protein; 18
or 30% fat) for a further 4 months period. While composition of finishing
diets significantly changed growth, nutrient utilization and body stores, a
significant consequence of first feeding composition was only observed on
fat depots. Visceral fat content was higher but dressing losses lower in
trout initially fed the 20% fat diet irrespective of the finishing diets.
(Nutrition,
Aquaculture and Genomics, INRA, 64310 Saint-Pée-sur Nivelle, France,
e-mail: edale@st-pee.inra.fr)