Four experiments were conducted to study of production meat in reared beluga (Huso huso) with different diets. In the first experiment, A 19-week feeding trial was conducted to evaluate dehulled soybean meal (DHSM) as a fish meal (FM) replacer in juvenile beluga, of initial body weight 8.25±0.08 g (mean±SD) in triplicate groups, fed six isoenergetic (20.1 mJ kg^-1) and isoproteic (45% crude protein) diets, resulting in 5%, 10%, 15%, 20% and 25% of fish meal protein being replaced by soybean protein. Growth performance was reduced significantly with the increasing of DHSM in the diets in the present study. In the next stage, triplicate groups of 315 fish averaging 300.25 ± 10.28 g (mean ± SD) were fed one of seven experimental diets for 14 weeks. Weight gain (WG), specific growth rate (SGR), feed effeciency (FE), protein efficiency of retio (PER) of fish fed 5%, 10% and 15% of soybean protein diets were significantly higher than those of fish fed 20%, 25% and 30% diets. Whole body protein, lipid, moisture content were unaffected among different treatments (P 〉 0.05). In the second experiment, A 2 × 4 factorial design was used to evaluate the dietary lysine and to determine the optimum dietary L-carnitine in sub-yearling beluga, reared in the indoor system. Twelve experimental diets were formulated and prepared to contain four lysine levels (0.75, 1.5, 2.25 and 4% diet) and two L-carnitine levels (300 and 600 mg/kg diet) at each lysine level. Fish averaging 23 ± 0.5 (mean±SD) were fed one of the experimental diets for 10 weeks. At the end of the experimental period, there were significant lysine and Lcarnitine effects (P 〈0.05) on growth performance and feed conversation ratio (FCR). These results may indicate that, weight gain (WG), FCR and protein efficiency ratio (PER) in fish fed diet containing 3% lysine and 600 mg L-carnitine/kg diet were significantly higher than those of fish fed control diet (P 〈 0.05). There were no significan dietary lysine and L-carnitine effects on glucose, cholesterol and haemoglobin (Hb) concentration, of fish fed different levels of lysine with 300 mg L-carnitine/kg diet, however, Hb concentration in fish fed diet containing 2.25% lysine and 600 mg L-carnitine/kg diet were significantly higher than those of fish fed control diet (P 〈 0.05). These results may indicate that the optimum lysine and the L-carnitine levels could be 2.25-3% and 600 mg L-carnitine, respectively in begga (8-300 4g), based on growth performance, feed utilization and hematological parameters. In the thired experiment, a study was conducted to evaluate the effects of dietary betafine and metionine interaction on the growth, feed efficiency, carcass composition and hematological index in juvenile beluga. Thirteen diets were formulated to contain four dietary metionine levels (0.5, 1, 1.5 and 2%), betafine (0.5, 1, 1.5 and 2%) with equal ratio of metionine and betafine (0.5: 0.5, 1: 1, 1.5: 1.5 and 2: 2% diet) were fed to juvenile beluga (23± 0.5 g) in triplicate groups for 12 weeks in a indoor system. The results showed that no significant (P〉 0.05) differences were found in growth performance and feed utilization among the dietary betafine and metionine concentrations in beluga. Hb concentration of fish fed control, 1 and 1.5% metionine were significantly higher than those of fish fed the other diets. FCR of fish was significantly improved by dietary metionine and betafine. FCR was lower (P 〈 0.05) in fish fed equal ratio of metionine and betafine (2: 2) diets than those in fish fed control diet. Based on above results, it is recommended that the diet for juvenile beluga, Huso huso (8-300g), should contain equal ratio of metionine and betafine (1.5: 1.5) diet, corresponding to 5.95 g/100 g of dietary protein for optimum growth, efficient feed utilization and whole-body protein content. A 17-week feeding trial was carried out to evaluate the effects of dietary L-carnitine level in beluga, Huso huso. A total of fish averaging 1247 ± 15.6 g (mean ± SD) were randomly distributed into 18 fibreglass tanks, and each tank holding 10 fish was then randomly assigned to one of three replicates of six diets with 50, 150, 350, 650, 950 and 1250 mg L-carnitine kg-1 diet. At the end of 17 weeks of feeding trial, average weight gain (WG), feed efficiency (FE), protein efficiency ratio (PER) and condition factor (CF) of fish fed 350 mg kg^-1 diet were significantly (P 〈 0.05) higher than those of fish fed 50, 150, 950 and 1250 mg kg-1 diets. WG, FE, PER and CF of beluga fed 650 mg kg^-1 diet were also significantly higher than those of fish fed 50, 950 and 1250 mg kg^-1 diets. Whole body and muscle protein were significantly improved by the elevation of dietary L-carnitine level up to 350 mg kg^-1. Liver superoxide dismutase and glutathione peroxidase activities of fish fed 350 and 650 mg kg^ -1 diets were significantly higher than those of fish fed 50, 950 and 1250 mg kg^-1 diets. The dietary Lcarnitine level of 350–650 mg kg^-1 diet could improve growth performance, feed utilization, protein-sparing effects of lipid, antioxidant defence system and reproductive success. Polynomial regression of WG suggested that the optimum dietary L-carnitine level was 480 mg kg^-1 diet. Therefore, these results may indicate that the optimum dietary L-carnitine could be higher than 350 but 〈650 mg kg^-1 diet in beluga reared in intensive culture conditions.
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