Dietary Lysine Requirement Of Fingerling Hybrid Clarias (Clarias Gariepinus X Clarias Macrocephalus)

Abstract

  The dietary lysine requirement of fingerling hybrid Clarias (Clarias gariepinus×Clarias macrocephalus) (4.2+0.03 cm, 0.056+0.04 g) was determined by feeding six isonitrogenous (400 g kg-1 crude protein) and isocaloric (17.9  kj  g−1) amino acid test diets containing casein, gelatin and L-crystalline amino acids with graded levels of lysine (10.0, 12.5, 15.0, 17.5, 20.0 and 22.5 g kg−1) for 4 weeks to triplicate groups. Diets were fed twice a day at 09:00 and 16:00 hours at 8% body weight−1. Maximum weight gain (523%), best feed conversion ratio (FCR, 1.41), Protein efficiency ratio (1.78) and specific growth rate (6.53%) were recorded in fish fed the diet containing lysine at 20.0gkg−1 of the diet. Second-degree polynomial regression analysis of live weight gain and FCR values indicated the dietary lysine requirement at 17.8 and 20.0 g kg−1  of dry diet respectively. Significantly higher carcass protein and protein deposition values were recorded at the requirement level (20.0 g kg−1). Higher fat and lower moisture values were obtained in carcass of fish fed the diet with 15.0g kg−1  lysine. The maximum carcass ash value was noticed in the fish fed at 20.0 g kg−1 dietary lysine. We recommend that the diet for hybrid Clarias (C.gariepinus× C.macrocephaluskg) should contain lysine in the range of 17.8–20.0 g kg−1 of the dry diet, corresponding to 44.5 and 50 g kg−1 of dietary protein respectively.

Keywords: - Lysine, fish, hybrid Clarias, dietary requirement, aquaculture