Effect of Rearing at Different Densities and Dietary Supplementation with Vitamin E on Growth Indices, Survival and Carcass Composition in Fingerling Rainbow Trout (Oncorhynchus mykiss)

This study was conducted to investigate the effect of rearing at differing densities and dietary supplementation with vitamin E on growth indices, survival and carcass composition in fingerling rainbow trout in a 6-week trial. Rainbow trout juveniles with initial body weight of 9.6 ± 0. 69 g at two densities of 50 and 100 pieces per 50 liter were fed two diets with the same protein and fat content. Experimental diets were diet 1 without adding vitamin and diet 2 with adding 600 mg/kg of vitamin E. A total number of 900 rainbow trout juveniles in four treatments, each in three replicates as T50(0) (with the density of 50 and feeding with diet 1), T100(0) (with the density of 100 and feeding with diet 1), T50(E) (with the density of 50 and feeding with diet 2) and T100(E) (with the density of 100 and feeding with diet 2) were randomly distributed. After 6 weeks of feeding, growth performance, feed conversion ratio and viability were significantly differentbetween treatments (P˂0.05). T50(0) and T50(E) had higher weight gain, specific growth rate and viability than T100(0) and T100(E) (P˂0.05). Feed conversion ratio was higher in T100(0) and T100(E) (P˂0.05). Carcass composition was not significantly differentbetween treatments (P˃0.05). The results showed that dietary vitamin E supplementation in rainbow trout juveniles did not have significant effect on growth, feed conversion,survival and carcass composition but density was a key factor in growth, feed conversion ratio and survival.