Effects of different levels of Folic acid and vitamin C in Rainbow trout (Oncorhynchus mykiss)

Abstract

Juvenile rainbow trout, Oncorhynchus mykiss (initial body weight 14 ± 0.25 g) were fed diets [crude protein 420 g/kg; gross energy 16.8 MJ/kg dry matter; crude fat 110 g/kg] containing deficient, adequate or excessive amounts of vitamin C and folic acid to investigate the potential nutritional effects on growth factors. A growth trial was conducted over 9 wks at a water temperature of 12 ± 1 °C. Four semipurified diets were supplemented with 0, 30, 60 and 90 mg /kg vitamin C and 0, 1, 2 and 3 mg/kg folic acid and were fed to fish in triplicate tank for 9 wks. At the end of the growth trial, the percent of survival, final body weight, weight gain, feed intake, feed conversion ratio, protein efficiency ratio and specific growth rate were measured. The results that growth factors were significantly (P < 0.05) affected by dietary vitamin levels. Inclusion levels of 2 mg/kg dietary folic acid and 60 mg/kg dietary vitamin C is acceptable, for use in rainbow trout diets, under favorable economic conditions. This study shows that increasing dietary folic acid and vitamin C could improve growth performance in juvenile rainbow trout.