Approaches to optimizing dietary protein to energy ratio for African catfish Clarias gariepinus (Burchell, 1822)

This is the authors' abstract. We don't add key points for this paper.

An 8-week feeding trial was conducted in a recycling water system at 28 ± 1 °C to investigate protein to energy ratio (P/E ratio) in African catfish Clarias gariepinus (10.9 ± 0.04 g). Six fishmeal-based diets of two protein levels (330 and 430 g kg−1), each with three lipid levels (40, 80 and 120 g kg−1) resulted in P/E ratios ranging from 15.5 to 21.3 mg protein kJ−1 gross energy (GE) were fed to 20 fish (per 30-L tank) in triplicate. Fish were fed 50 g kg−1 of their body weight per day adjusted fortnightly. Significantly higher (P   0.05) values of protein utilization were found in-between the both (higher and lower) protein diets. Higher lipid deposition (P   0.05). Digestive enzyme activities (protease and lipase) and histological examination of intestine and liver of fish fed varying P/E diets found no significant differences in response to experimental diets. The study reveals that African catfish C. gariepinus performed best the diet containing 430 g kg−1, 21.2 kJ g−1 and 20.5 mg protein kJ g−1 GE protein, gross energy and P/E ratio, respectively.