Effects of dietary l-carnitine supplements on growth and body composition in beluga sturgeon (Huso huso) juveniles

Abstract

Summary The effects of dietary l-carnitine on growth performance, whole body composition and feed utilization were studied in beluga, Huso huso. Fish were randomly allocated in 15 tanks (30 fish per tank) and triplicate groups were fed to satiety during 84 days one of five isonitrogenous (41% CP) and isoenergetic (20 MJ kg−1) diets, each differing in l-carnitine content [0 (control), 300, 600, 900 and 1200 mg kg−1 diet]. At the end of the trial, fish grew from 19- to 23-fold in weight, from 8.4 g to a maximum of 191 g. Fish fed 300–600 mg l-carnitine had the highest specific growth rate (SGR, 3.69 and 3.72% day−1) and protein efficiency ratio (PER, 0.95 and 0.99), and the lowest feed conversion ratio (FCR, 1.4 and 1.3) than the other groups (P < 0.0001). SGR, PER and FCR were the poorest for fish fed 1200 mg l-carnitine, while fish fed the unsupplemented and 900 mg l-carnitine supplemented diet showed intermediate performance. Body lipid concentration decreased significantly from 5.8 to 5.1% (P < 0.0001) with dietary l-carnitine supplementation increasing from 0 to 300 mg. Energy content was significantly lower in fish fed the 900 and 1200 mg l-carnitine diet (5.8 MJ kg−1), when compared with the other treatment groups (6.4–6.6 MJ kg−1). The results indicated that feeding sturgeon on diets supplemented with 300 mg l-carnitine kg−1 diet improved growth performance, and stimulated protein-sparing effects from lipids.