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

An 8-week feeding trial was conducted in a recycling water system at 28 +/- 1 degrees 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,...

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Bibliographic Details
Published in:Aquaculture nutrition 2005-04, Vol.11 (2), p.95-101
Main Authors: Ali, M.Z, Jauncey, K
Format: Article
Language:English
Subjects:
African catfish (Clarias gariepinus)
animal growth
body composition
catfish
Clarias
Clarias gariepinus
dietary protein
dietary protein and lipid levels
digestible energy
digestive enzymes
energy content
enzyme activity
feed composition
feed conversion
fish culture
fish feeding
glycogen
histology
intestines
lipid content
liver
liveweight gain
protein content
protein to energy ratio
protein utilization
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Summary:An 8-week feeding trial was conducted in a recycling water system at 28 +/- 1 degrees 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) growth rates and feed conversion efficiency were evident in fish fed with higher protein diet. The highest growth rate was found by fish fed 430 g kg(-1) protein, 21.2 kJ(-1) GE with a P/E ratio of 20.5 mg protein kJ(-1) GE. Significantly indifferent (P > 0.05) values of protein utilization were found in-between the both (higher and lower) protein diets. Higher lipid deposition (P < 0.05) in whole body and liver was observed with increasing dietary lipid level at each protein diet and as higher (P < 0.05) for the lower protein diets. Liver glycogen tended to decrease with increasing gross energy at each protein diet and higher protein diet showed comparatively lower values (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.
ISSN:1353-5773
1365-2095
DOI:10.1111/j.1365-2095.2004.00325.x