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Effect of varying dietary energy level on feed intake, feed conversion, whole‐body composition and growth of Malawian tilapia, Oreochromis shiranus – Boulenger
Author(s) -
Kang'ombe Jeremiah,
Likongwe Jeremy S.,
Eda Hiroki,
Mtimuni Joshua P.
Publication year - 2007
Publication title -
aquaculture research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.646
H-Index - 89
eISSN - 1365-2109
pISSN - 1355-557X
DOI - 10.1111/j.1365-2109.2007.01676.x
Subject(s) - biology , tilapia , feed conversion ratio , zoology , body weight , composition (language) , oreochromis , weight gain , protein efficiency ratio , juvenile , fish <actinopterygii> , fishery , ecology , endocrinology , linguistics , philosophy
Four isonitrogenous [30% crude protein (CP)] diets containing different gross energy levels (13.39, 16.74, 20.50 and 23.85 kJ g −1 ) were evaluated to determine the optimum energy for the Malawian tilapia Oreochromis shiranus . Each tank (120 L) was stocked with 18 juvenile tilapia (average weight 7.32±0.25 g) and they were fed the experimental diets for 10 weeks. The final average weight of the fish was approximately twofold higher (range: 12.64–16.77 g) than the initial weight. The dietary energy significantly ( P <0.05) influenced growth. The average weight of fish fed dietary energy level 20.50 kJ g −1 was significantly higher ( P <0.05) than the weight of the fish fed any of the other experimental diets. There was no significant difference in growth of fish fed 13.39 and 16.74 kJ g −1 energy levels, but 23.85 kJ g −1 produced the lowest growth rates. There were no significant differences ( P >0.05) between feed intake across the treatments. Feed conversion ratio (range: 2.2–3.0) and protein efficiency ratio (range: 1.10–1.50) among the dietary treatment groups were in agreement with trends for weight gain. Dietary energy level significantly ( P <0.05) influenced the body composition of O. shiranus . Whole‐body moisture (range: 64.27–67.15%) and ash (range: 13.21–14.73%) decreased in all treatments. Whole‐body protein (range: 63.57–66.16%) increased only in groups fed on the diet containing 20.50 kJ g −1 . Whole‐body fat (range: 13.58–17.27%) and gross energy (range: 28.411–33.210 kJ g −1 ) increased significantly ( P <0.05). Fish survival was 100% in all treatments. The results demonstrated that to maximize growth at a temperature of 23°C, O. shiranus should be fed diets containing 20.50 kJ g −1 gross energy.