Effect of native and modified starches on nutritional and physiological performance of wild juveniles of red grouper (Epinephelus morio)

Abstract

The aim of this study was to evaluate carbohydratesutilization by wild red grouper Epinephelus morio.Juveniles were fed during 93 d on a selection of starches: native raw cornstarch (RCS), waxy cornstarch (WCS), raw potato starch (RPS) and gelatinized potato starch (GP) at 20% inclusion level. The best growth was obtained in fish fed cornstarch either native raw of waxy cornstarch (p<0.05). Hepatosomatic index and blood glucose (40 mg dL-1) were similar as well as hematocrit values (50%) (p>0.05), whereas glycogen content increased up to 200 mg g-1with waxy cornstarch. Specific activity of a-glucosidase and α-amylase remained stable (p>0.05). Hepatic glycolytic enzymes increased with raw native and waxy cornstarch (p<0.05); metabolic enzyme glucose 6 phosphate dehydrogenase (G6P-DH) was activated with raw native cornstarch (p<0.05) while pyruvate kinase (PK) remained stable regardless of treatments (p>0.05). Hexokinase (HK1) and glucokinase (GK) varied according to carbohydrate source: values were higher with cornstarches than potato starches (p<0.05).  Pentose monophosphate shunt (HMS) remained not altered by starch sources (p>0.05). In final, the low size of granules from cornstarch favored the assimilation in liver of wild juveniles red grouper.