Brook charr reared for 30 days at a high stocking density (120 kg/m3) had significantly lower final body weight and reduced food consumption when compared to fish reared at a lower stocking density (30 kg/m3). There was no effect of stocking density on plasma cortisol and T3 concentrations, while plasma T4 concentration was lowered in fish held at high stocking density. Plasma glucose levels, liver glycogen content and hepatosomatic index were significantly lower in fish reared at high stocking density, while plasma protein and free fatty acid (FFA) levels were not significantly different between groups. There were significantly higher activities of hepatic phosphofructokinase, fructose biphosphatase, 3-hydroxyacyl CoA dehydrogenase, glycerol kinase and glycerol-3-phosphate dehydrogenase in fish held at high stocking density compared with those at low stocking density. Hepatic hexokinase and glucose-6-phosphate dehydrogenase activities were significantly lower in fish at high stocking density compared with those at low stocking density, while there were no differences in pyruvate kinase, glucose-6-phosphatase, phosphoenolpyruvate carboxykinase, glutamate dehydrogenase, glutamate pyruvate transaminase and glutamate oxaloacetate transaminase between the groups. These results suggest that high stocking density has the effect of mobilizing triglyceride sources, promoting gluconeogenesis from glycerol, but has little effect on protein metabolism.
Brook charr reared for 30 days at a high stocking density (120 kg/m3) had significantly lower final body weight and reduced food consumption when compared to fish reared at a lower stocking density (30 kg/m3). There was no effect of stocking density on plasma cortisol and T3 concentrations, while plasma T4 concentration was lowered in fish held at high stocking density. Plasma glucose levels, liver glycogen content and hepatosomatic index were significantly lower in fish reared at high stocking density, while plasma protein and free fatty acid (FFA) levels were not significantly different between groups. There were significantly higher activities of hepatic phosphofructokinase, fructose biphosphatase, 3-hydroxyacyl CoA dehydrogenase, glycerol kinase and glycerol-3-phosphate dehydrogenase in fish held at high stocking density compared with those at low stocking density. Hepatic hexokinase and glucose-6-phosphate dehydrogenase activities were significantly lower in fish at high stocking density compared with those at low stocking density, while there were no differences in pyruvate kinase, glucose-6-phosphatase, phosphoenolpyruvate carboxykinase, glutamate dehydrogenase, glutamate pyruvate transaminase and glutamate oxaloacetate transaminase between the groups. These results suggest that high stocking density has the effect of mobilizing triglyceride sources, promoting gluconeogenesis from glycerol, but has little effect on protein metabolism.
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