Heat treatment affects protein quality and protease activity in decapsulated cysts of Artemia when used as starter food for larvae of African catfishClarias gariepinus (Burchell)

Decapsulated cysts of Artemia subjected to different heat treatments (40, 6 0, 80 and 96 degrees C) were fed to African catfish Clarias gariepinus larv ae. Heated cysts, untreated cysts and live Artemia nauplii as control const ituted the experimental diets. Protein denaturation and solubility, total a lkaline protease and specific trypsin activities in the cyst diets were eva luated. The growth of catfish larvae and the proteolytic activity of larval samples during development were also determined. Heat treatment of cysts i ncreased protein denaturation and decreased protein solubility. The proteas e activity in the cyst diets decreased with higher heating temperatures. Th e growth of catfish larvae differed according to the diet; higher fish grow th was achieved with nauplii and cysts heated at 40 degrees C. The digestiv e enzyme activity in larval samples remained similar in all dietary treatme nts during larval development. The quality of food protein and the way this protein is processed might be more important for successful larval growth than exogenous enzyme supply.