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.