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). At the end of the experiment, in fish refed for 5 weeks following a feeding-starvation cycle and in 10-week fed animals, the higher levels of blood glucose, triglycerides and cholesterol were found in fish fed low-protein diets (p < .05). In all treatments, 2 weeks of starvation decreased α-amylase activity in the intestine (p < .05), while 4 days of refeeding increased lipase (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.