Dietary Methionine Requirement of the African Catfish, Clarias gariepinus

ABSTRACT

A growth study was conducted to quantify the dietary methionine requirement (in the absence of cystine) of the African catfish, Clarias gariepinus, using diets containing casein and gelatin as sources of intact protein, supplemented with crystalline amino acids. Amino acid test diets (400 g/kg crude protein; 3.0 kcal gross energy/g dry matter) with graded levels of methionine (20-40 g/kg protein) were formulated and fed to triplicate groups of African catfish (18.7 ±1.8 g) twice a day up to satiation for 70 days. Anorexia was observed after one week in catfish fed with diets containing 20-24 g methionine/kg protein. Dietary methionine requirement estimated using break point analysis was 32 g/kg dietary protein. No diet-related mortality or cataract were observed in catfish fed any of the diets.