15 SEPTEMBER 1999
EFFECT OF DIETARY N-3 HUFA ON GROWTH AND BODY COMPOSITION OF JUVENILE YELLOWTAIL FLOUNDER (PLEURONECTES FERRUGINEUS)
K.S. Whalen, J.A. Brown, C.C. Parrish, S.P. Lall, J.S. Goddard-1998
Bulletin of the Aquaculture Association of Canada, 98-2 (contributing papers Aquaculture Canada '98): 21-22
Abstract:
In order to develop grower diet for marine flatfish for aquaculture in Newfoundland, the effect of n-3 highly unsaturated fatty acids (HUFA) on the growth of juvenile yellowtail flounder (Pleuronectes ferrugineus) was studied. Most cold-water fish require high levels of n-3 HUFA in their diets for biological functions, including membrane fluidity. Juvenile yellowtail flounder were fed standard ICES diets containing varying levels of n-3 HUFA ranging between 0.4 and 2.5%, and a commercial diet. Juvenile fish (0+) weighing 1.92 +/- 0.50 g were fed for 12 weeks in triplicate treatments. Experimental diets, fish liver, and muscle were analysed for proximate and fatty acid composition. Although no mortalities were observed, fish fed the lower n-3 HUFA levels showed significantly lower growth than those fed the commercial diet and 2.5% HUFA diet. Significant trends were also found in the biochemical compositions of the fish in the various treatments. Fish fed the 0.4% n-3 HUFA diet had the highest levels of lipid in the liver and the lowest levels in the muscle; however, hepatosomatic indices showed no significant differences among treatments. Triacy1glycerol levels were highest in the livers and lowest in the muscle of the fish fed the diet lowest in n-3 HUFA and lipid transport may have been impaired in these fish, indicating an essential fatty acid deficiency. Fatty acid composition in both liver and muscle was affected by diet. Fish fed the 0.4% diet preferentially conserved the n-3 HUFA in the polar lipid fraction. Results suggest that juvenile yellowtail flounder require approximately 2.5% n-3 HUFA in their diets on a dry weight basis.
(Ocean Sciences Centre, Memorial University of Newfoundland, St. John's, NF, Canada A1C 5S7)