Effects of dietary protein and lipid levels on performance and carcass composition of fingerling carp.

A 6-week feeding study was carried out to determine the effects of dietary protein (casein-gelatin at 26, 30, 34% supplemental levels) and lipid (5% feed oil +0, 4.5, 9.5% beef tallow) levels in semi-purified diets for fingerling carp at 25°C. Increasing the dietary protein levels from 26 or 30% to 34% significantly improved weight gain in almost all lipid levels, but supplement of lipid slightly depressed the growth at all protein levels. On the other hand, lipid supplement showed essentially no effect on feed efficiency, but increment in protein level by only 4% from either 26 or 30% resulted in almost 10% better feed efficiency. Food consumption was not affected by the protein level and tended to decline with increase in lipid level. Dietary treatments failed to show any significant effect on the carcass protein content, but the carcass lipid became higher with increase of the dietary lipid and decrease of the protein. Neither dietary protein nor lipid levels showed significant effect on efficiency in protein and energy utilizations and no significant interaction between these two was detected, However, highly significant correlation coefficients were noted between DE/P and the performance or carcass composition of the fish, and the best result was obtained at a DE/P value of about 100.