Compensatory growth, antioxidant capacity and digestive enzyme activities of Sobaity ( Sparidentex hasta ) and yellowfin seabreams ( Acanthopagrus latus ) subjected to ration restriction

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The compensatory growth response (CGR) and some selected physiological parameters were evaluated in sobaity (Sparidentex hasta, 10 g) and yellowfin seabreams (Acanthopagrus latus, 4.3 g) juveniles subjected to a 2-week restricted feeding. Fish were first fed at 0%, 25%, 50% and 75% of the satiation level for a 2-week period, and then, they were refed for 6 weeks at the visual satiation level. The control group was fed to the satiation everyday for 8 weeks. Three hundred sobaty seabream juveniles were stocked into 15 tanks (20 fish tank−1), and 450 yellowfin seabream juveniles were allocated into 15 tanks (30 fish tank−1) and were fed on a commercial feed (500 g kg−1 crude protein and 150 g kg−1 crude fat). Survival rate was decreased in R0% group in S. hasta because of the cannibalism, which was triggered by feed restriction. After the 2 weeks of feed restriction, the control and R0% treatments in S. hasta (16.0 vs. 9.3 g) and A. latus (3.9 vs. 6.2 g) had the highest and lowest body weight, respectively. After the 6 weeks of refeeding trial, all the ration-restricted groups showed a full CGR in S. hasta. Regarding A. latus juveniles, except for R0%, the other groups showed a full CGR. Feed conversion ratio was improved in S. hasta that subjected to the 2-week feed restriction, but this parameter did not change in A. latus. Antioxidant enzyme activities in the liver of S. hasta juveniles, including glutathione-S-transferase, glutathione peroxidase, superoxide dismutase and catalase along with liver enzymes including alkaline aminotransferase, aspartate amino transferase, lactate dehydrogenase and alkaline phosphatase gradually were decreased with reducing the severity of the feed restriction. Regarding A. latus, all mentioned antioxidant and the liver enzymes in the feed-restricted groups were higher than the control. R75% and control groups in S. hasta had the greatest and the least trypsin and alkaline phosphatase activities. In A. latus, R25%, R50% and R75% groups had higher trypsin, chymotrypsin and lipase activities compared with the other groups (p < .05). By considering all the selected physiological responses in both species, it can be concluded that increasing the feed restriction severity can trigger oxidative stress that may compromise health condition.