ABSTRACT
Background:Vitamin C is one of the important nutrients in fish culture and as a potent anti-oxidant, is of great importance in preserving cells against oxidation and boosting resistance in stress conditions and against pathogens
Objectives: The purpose of the present study is to add high level of vitamin C supplementation to rainbow trout [Oncorhynchus mykiss] diet reared at high density and analysis of growth indices, survival and carcass composition at two different stocking densities
Methods: Rainbow trout juveniles with initial body weight of 9.6 +/- 0.69 g at two densities of 50 and 100 pieces in 50 liters of water were fed two diets containing the same level of protein and fat. Experimental diets were diet 1 without adding vitamin and diet 2 with adding 1500 mg/kg of vitamin C. A total number of 900 rainbow trout juveniles in four treatments each with three replicates as T50 [0] [with the density of 50 and fed with diet 1], T100 [0] [with the density of 100 and fed with diet 1], T50 [C] [with the density of 50 and fed with diet 2] and T100 [C] [with the density of 100 and fed with diet 2] were randomly distributed in incubators
Results:After 6 weeks of feeding, growth indices, feed conversion ratio and viability were significantly different between treatments [p<0.05]. T50 [0] and T50[C] treatments had higher weight gain, specific growth rate and viability than T100 [0] and T100[C] [p<0.05]. In the case of feed conversion ratio, it was higher in T100 [0] and T100[C] treatments compared to T50 [0] and T50[C] ones [p<0.05]. Carcass composition was not significantly different between treatments [p>0.05]
Conclusions: The results showed that vitamin C supplementation in the diet of rainbow trout juveniles did not have significant effects on growth indices, feed conversion ratio, survival and carcass composition but density was a key factor in growth, feed conversion ratio and survival in this species