Effects of supplemental dietary L-carnitine on growth and body composition of beluga (Huso huso) juveniles.

The effect of feed supplemented with l-camitine at four levels of 0, 300, 600 and 900mg kg^-1 on growth performance and body composition of beluga, h. huso, juveniles was evaluated in two separatetrials. in the first trial, 180 juveniles (525±9g) were fed with the test diet for a period of 71 days, and the trial extended to another 126 days in the second phase by randomly selecting 120 juveniles (870.7±32g) and rearing them with similar diets. all trials, in triplicates, were conducted in circular fiberglass tanks (200cm diameter,40cm height). the fish were fed 4 times daily to apparent satiation. in the first phase, l-carnitine did not significantly affect mean final weight, feed conversion ratio (fcr) or specific growth rate (sgr) of the fish, however, the fish receiving 900mg kg^-1 l-carnitine showed better growth increment, sgr and feedefficiency (fe) than those in control group (p >= 0.05); neither did it significantly affect protein, lipid, moisture or ash as well as hepatosomatic index (hsi) (p >= 0.05). the protein efficiency ratio (per) was significantly affected by l-carnitine supplemented diet, particularly at 900mg kg^-1 (p=<0.05). in the second phase, fish fedl-carnitine-supplemented diets produced significantly higher w2, sgr and per than the control group (p<=o.05), but hsi decreased significantly (p<=0.05). at the end of the trial, the whole body composition of fish did not differ significantly among experimental treatments, but slightly reduced lipid content were observed at 600 and 900mg kg^-1 l-carnitine (p>=0.05). the results of this study indicated that supplementation of diets with 300-600mg carnitine kg^-1 improved growth rate, feed utilization and stimulated protein-sparing effect in this species.