The effect of different levels of dietary niacin and carbohydrate on growth performance, carcass composition and heamolymph biochemical parameters of juvenile whiteleg shrimp (Litopenaeus vannamei)

In this study, the effect of experimental diets containing different levels of carbohydrate and niacin on growth indices, carcass composition and heamolymph biochemical parameters of juvenile whiteleg shrimp (Litopenaeus vannamei) were investigated for 45 days. Shrimp with mean initial weight of 5±0.33 g were reared in 300 liter tanks with 8 treatments. Feeding was performed 4 times a day using experimental diets containing two levels of carbohydrate 15 and 30% and three levels of dietary niacin 100, 150 and 200 mg kg-1with two controls. At the end of the period, growth indices, carcass composition and biochemical indices of heamolymph of shrimps were assessed. The best growth performance consisted of the highest final weight (14.05±0.5 g), final length (13.38 ± 0.05 cm) and specific growth rate (2.23±0.07) were in treatment contained 15% carbohydrate and 100 mg niacin kg-1 diet (p<0.05). Also, the highest glucose (53.66±0.88 mg dl-1), HDL (27±0.57 mg dl-1) and total protein values (10.9 ± 0.17 mg dl-1) were in  treatment contained 15% carbohydrate and 100 mg niacin kg-1 diet (p<0.05). On the other hand, the highest protein content of carcass was observed in treatments contained 15% carbohydrate and 100-150 mg niacin kg-1 diet (p<0.05). Also, fat of carcass was reduced by decreasing dietary carbohydrate (p<0.05). Therefore, the results showed that low carbohydrate level with 100 mg niacin per kg of diet had beneficial effects on growth, carcass composition and heamolymph of juvenile whiteleg shrimp.