Effects of dietary protein and energy on growth, feed conversion efficiency, and body composition of Tilapia aurea

Abstract

The optimum dietary protein to energy ratio (P:E ratio) for rapid and. efficient gain of juvenile Tilapia aurea was shown to vary with growth. The optimum concentration of protein and energy also varied with growth. Although numerical differences between individual diets were not statistically significant in every case, a diet providing roughly 56% protein and 4600 kcel/kg with a P:E ratio of 123 mg protein/kcal produced highest gain of fry (2.5 g). By the time the fish reached 5.0 g, 46% protein and 4000 kcal/kg with a P:E ratio of 115 produced best growth. In 7.5 g fish a 34% protein, 3200 kcal/kg diet with a P&E ratio of 108 gave hignest gains. Feed conversion was consistently superior on lower P:E ratio diets and was best on a, 34% protein, 3200 kcal/kg diet. Linear regression analysis indicated highly significant differences in average fish weight, condition, and feed conversion efficiency attributable to changes in either protein or energy concentration. Significant interaction between protein and energy was also demonstrated. No significant differences occurred in survival. Condition and level of carcass fat were high on all diets which produced good growth rates and were inversely related to the P:E ratio. Moisture and ash were inversely related to carcass fat. No trend was established for carcass protein.