Utilisation of a carbohydrate-rich diet by common carp reared at 18 and 25degrees C

The effect of water temperature on the utilisation of dietary starch by car p was studied through measurements of growth performance, body composition, plasma glucose levels, ammonia excretion and energy expenditure performed for 10 weeks with fish reared at 18 and 25 degrees C. Apparent digestibilit y coefficients of energy and nutrient including starch were higher at 25 de grees C than at 18 degrees C. Ingestion of a diet containing high level of carbohydrate does not induce an hyperglycaemia in carp.;Plasma glucose cont ent increased after feed intake but the highest values were around 1 g/l, i rrespective of the water temperature. In carp grown at 25 degrees C, the hi ghest values were observed earlier than in carp at 18 degrees C and the bas al level was reached more rapidly. At the end of the 10-week growth trial, body fat content was higher in fish reared at 18 degrees C. In these fish, heat increment of feeding represented a largest part of digestible energy b ut basal energy needs were 1.8 times lower than in carp reared at 25 degree s C. Moreover, energy supply from lipid was decreased which led to an incre ase in fat gain. Protein gain was not affected by water temperature.