Interactions of dietary levels of protein and energy on fingerling snakehead, Channa striata

Abstract

A 4 × 3 factorial experiment was conducted to determine the optimum protein to energy ( P E ) ratio for fingerling snakehead. Four crude protein levels and three energy levels at each protein level were utilized. Laboratory-made brown fish meal was used as the major source of protein in all the test diets. Each of the experimental diets was fed to triplicate groups of 15 fingerlings with an average individual weight of 12 g in 110-1 flow-through fibre blast tanks at 28 ± 2 °C, with 5.9 to 7.2 mg dissolved oxygen 1 −1. The diets were fed at a rate equalling 3 wet body wt% day −1 in two equal rations and adjusted weekly for 8-weeks. The highest growth was attained by fingerlings fed a 40% protein diet with a P E ratio of 90.9 mg protein kcal −1 digestible energy. A lower but not significantly different ( P > 0.05) growth response was attained by fingerling fed a 45% diet with a P E ratio of 93.8 mg kcal −1. Protein efficiency ratio (PER) was affected by the increase in energy level from 400 to 480 kcal 100 g −1 at all protein levels except 40% where a diet with energy 440 kcal 100 g −1 showed maximum PER value. The lowest feed conversion ratio (FCR) was obtained at an P E ratio of 90.9 mg protein kcal −1. Carcass moisture content was not affected by dietary P E ratio. Other changes in carcass composition due to the change in dietary P E ratio were not consistent. This study also indicated that a lipid level of 13% can be effectively utilized by snakehead fingerlings without any adverse effects.