Effect of diet composition on growth performance, hepatic metabolism and antioxidant activities in Siberian sturgeon (Acipenser baerii, Brandt, 1869) submitted to starvation and refeeding

Many fish species undergo natural starvation periods. Adaptation to starvation is possible through the activation of behavioral, biochemical and physiological mechanisms. Knowledge of the effect of dietary nutrients on the intermediary metabolism during starvation and refeeding can be useful to improve fish health and optimize aquaculture production. To analyze the effect of dietary nutrients on liver metabolism of Siberian sturgeon (Acipenser baerii) submitted to starvation and refeeding, four isoenergetic diets differing in nutrient composition were designed: LP-St (38 % protein, 12 % lipid, 36 % carbohydrate), HP-St (44 % protein, 10 % lipid, 30 % carbohydrate), LP-L (38 % protein, 18 % lipid, 25 % carbohydrate) and HP-L (44 % protein, 16 % lipid, 22 % carbohydrate). Four groups of fish were fed 3 weeks to satiety with the corresponding diet, starved for 2 weeks and then refed 5 weeks to satiety on the same diet. Starvation mobilized the hepatic lipid store to a greater extent than glycogen. Starvation increased superoxide dismutase activity irrespective of the diet, while low protein diets (LP-St and LP-L) increased catalase activity. The oxidative damage decreased after 5 weeks of refeeding. Refeeding the starved fish on the HP-St diet promoted the greatest growth performance. In addition to report for the first time the effect of diet composition on growth, liver composition and antioxidant activities in Siberian sturgeon submitted to starvation and refeeding, our findings suggest that refeeding on HP-St diet stimulated the use of dietary carbohydrates and allowed a protein sparing effect in Siberian sturgeon

Impact of starvation on digestive enzymes activities and plasma metabolites in Siberian sturgeon (Acipenser baerii, Brandt, 1869)

To increase the current knowledge about the relationship between nutritional status and the digestive capacity of Siberian sturgeon (Acipenser baerii), we addressed the effect of starvation-refeeding and macronutrient composition on growth parameters and key digestive enzyme activities in A. baerii. Acipenser baerii juveniles were fed four different diets for 3 weeks, then starved for 2 weeks and allowed to refed for 5 weeks with the same diets. Another group of fish were fed 10 weeks with the corresponding diets. Among 10-week fed fish, high-protein diets promoted higher body weight values, while the lowest specific growth rate was observed in fish fed a low-protein, medium-carbohydrate, high-lipid diet (p .05) and α-amylase activity in the intestine as well as pepsin in the stomach (p < .05). Our findings suggest that A. baerii maintains a high capacity to digest proteins and lipids after 2 weeks of starvation and that α-amylase can be used as an indicator of the nutritional status in fish submitted to starvation-refeeding cycles. Indeed, refeeding with high-protein and CHO:L ratio diets after starvation could improve the growth rate of A. baerii in culture