A dynamic simulation model for growth of the African catfish, Clarias gariepinus (Burchell 1822) : IV. The effect of feed formulation on growth and feed utilization

Abstract

A dynamic simulation model is used to calculate growth of Clarias gariepinus (Burchell) fed with differently formulated diets. To verify the calculations, the results of the simulation are compared with experimental data. The experiments were carried out to determine the growth performance of C. gariepinus, fed with diets containing different protein sources. A fish meal diet was fed at four feeding levels in a respiration experiment. The alternative sources (blood meal, casein, groundnut, cottonseed, rapeseed and soybean) were tested at various inclusion rates with fish meal in aquarium experiments at one feeding level. Both experiments lasted two periods of 4 weeks each. The output of the simulation model, being fresh weight gain, protein gain, fat gain, oxygen consumption and ammonia production, agreed well with results from the respiration experiment, except for fat gain at the highest feeding levels and ammonia production in the second experimental period. It was shown that C. gariepinus is able to convert feed nutrients very efficiently into fish biomass. A protein conversion efficiency of nearly 60% was found. In the aquarium experiments the fresh weight gain decreased when an increasing part of the fish meal was replaced by alternative protein sources. The output of the simulation model (fresh weight gain) in comparison with the experimental results showed that it is possible to calculate the weight conversions of differently formulated diets, when there is a reliable estimation of the amino acid composition of the protein sources used.