Dietary lipid to carbohydrate ratio in beluga,Huso huso(Linnaeus, 1758), fed two L-carnitine levels

A feeding experiment was carried out to determine the optimal dietary lipid: carbohydrate ratio (L:CHO, in %) on growth performance and feed efficiency in beluga, Huso huso (Linnaeus, 1758), juveniles fed two L-carnitine supplementation levels. Triplicate groups (25 fish/tank) were fed one of eight isoproteic (41% crude protein) and isoenergetic (20 kJ kg−1 diet) diets with increasing L:CHO ratios (12 : 21, 15 : 16, 18 : 5 and 21 : 0) and one of two L-carnitine supplements (0 or 300 mg kg−1). Fish (initial body weight 480 ± 18.4 g) were housed in 24 fiberglass tanks and fed to apparent satiation for 114 days. Fish fed the 18 : 5: and 21 : 0 had higher weight gain, growth rate, feed conversion ratio and protein efficiency ratio than fish fed the other diets. Growth performance was significantly improved by supplementing 300 mg L-carnitine to diets. Liver lipid increased with increasing dietary L:CHO ratios and decreased with dietary L-carnitine level. These results indicated that juvenile beluga did not utilize dietary carbohydrate as efficiently as lipid. Moreover, diets with a dietary lipid:CHO ratio between 18 : 5 and 21 : 0 and supplemented with 300 mg L-carnitine kg−1 successfully improved growth performance and feed utilization of beluga sturgeon reared in intensive culture conditions.