Carbohydrate utilization by tilapia (Oreochromis niloticus x O. aureus) as influenced by different chromium sources

An experiment was conducted to study the influence of three different forms of chromium (CrCl3.6H2O, Na2CrO4.4H2O and Cr2O3) on the utilization of two carbohydrates (glucose and cornstarch) by juvenile hybrid tilapia (Oreochromis niloticus x O. aureus). Average initial body weight of the fish was 1.13 +/- 0.02 g. Fish were fed 5% body wt/d. Significantly (P < 0.05) greater body weight gain, food intake, protein retention, energy retention and body lipid concentration were observed in fish fed the starch diet than in those fed the glucose diet. Fish fed the glucose diet supplemented with any type of chromium had significantly greater weight gain than those fed the glucose diet without chromium supplementation. Fish fed the glucose diet supplemented with Cr2O3 had greater weight gain, food intake, protein retention, energy retention and body lipid concentration than those fed the unsupplemented glucose diet or the glucose diet supplemented with CrCl3.6H2O or Na2CrO4.4H2O. Delayed plasma glucose peak time was observed in tilapia fed the glucose diet supplemented with any type of chromium. Chromium supplementation generally lowered the glucose-6-phosphatase activity in tilapia. Phosphofructokinase activity was significantly higher in fish fed the glucose diet supplemented with Cr2O3 than in the other glucose-fed groups. These data suggest that chromium supplementation improved glucose utilization by tilapia and that Cr2O3 supplementation was markedly more effective than other chromium forms.