Abstract
During the rearing period, fish may be exposed to fasting due to low or high temperatures, transportation, handling, and other stressors, while they may catch-up the growth differently after supplying the feed. The aim of this study was to investigate the compensatory growth (CG) response of juvenile Siberian sturgeon Acipenser baerii after restricted feeding. In the first phase (60 days), triplicate groups of fish were subjected to feed restriction (25%, 50%, and 75% of the amount needed to reach satiation, respectively) or satiation feeding (control) and in the second phase all treatment groups were fed to satiation for an additional 60 days. Growth performance was measured during the two phases and blood samples were collected at the end of the second phase to measure blood biochemical indices. At the end of the first phase of the experiment, as expected, the control group showed the highest mean body weight, followed by the 75%, 50% and 25% satiation fed groups (P < 0.05). However, at the end of the second phase, the final body weights were not significantly different between the groups (P > 0.05), while some of the growth performance improved in the 25% satiation fed group (P < 0.05). At the end of the second phase, serum metabolites except for glucose and cholesterol were significantly different among treatment groups, with the highest levels in the control group. Feed restriction significantly lowered hematocrit, total protein and triglyceride levels especially in the 25% satiation fed group (P < 0.05). The results showed that juvenile Siberian sturgeon could tolerate feed restriction without any significant negative impacts on the majority of growth and metabolite indices. In conclusion, using an appropriate feeding regime helps to improve feed efficiency with no physiological impacts on Siberian sturgeon rearing.