requirements of n-3 highly unsaturated fatty acids in beluga (huso huso) juvenile and their effects on growth, carcass quality and fatty acids composition

an 8-week feeding experiment was carried out on beluga (huso huso) juvenile to evaluate the effects of different levels of fish oil containing n-3 highly unsaturated fatty acids (n-3 hufas) on fish growth and fatty acid composition. the requirements of beluga juvenile for n-3 hufas were studied by feeding fish diets containing six different levels of n-3 hufas ranging from 1.56 to 17.25% (% of total fatty acids). weight gain, feed conversion ratio, condition factor, specific growth rate and protein efficiency ratio were not significantly different among dietary treatments, nor was the body composition (including: moisture, protein, lipid and ash) of beluga juvenile (p> 0.05). there were no significant differences among plasma protein, glucose, cholesterol and triglyceride contents of dietary treatments (p> 0.05). however, haematocrit values were significantly lower in diets 1 and 2 (p< 0.05). the fatty acid composition of fish showed a pronounced change from the initial carcass with fatty acid composition changes in experimental diets. the fatty acid composition of the beluga carcass fed on diets containing various levels of n-3 hufas reflected the dietary fatty acid composition. the n-3 hufas contents of the lipids of fish increased with an increase in dietary n-3 hufas levels. results suggested that minimum levels of n-3 hufas in diet have no effect on growth and n-3 hufas are not a restrictive factor on growth in beluga.