Pond farming of Nile tilapia, Oreochromis niloticus (L.) in northern Cameroon. Comparing two different strategles for feeding cottonseed cake in tilapia male monosex culture |
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| Authors: | A J Middendorp E A Huisman |
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| Institution: | Department of Fish. Culture and Fisheries, Wageningen Agricultural University, Wageningen, The Netherlands |
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| Abstract: | Two cottonseed cake feeding strategies were tested in pond culture of hand-sexed male Nile tilapia, Oreochromis niloticus (L.). (W0 > 80 g), with the objective of making better use of the algal blooms which develop when cottonseed cake is applied to a pond. In the conventional ‘progressive feeding strategy’, the daily amount of cottonseed cake was adjusted monthly for the total tilapia bioweight estimated from sampling, assuming that cottonseed cake primarily acted as a tilapia feed. In the ‘linear feeding strategy’, ponds received a fixed daily amount of cottonseed cake throughout the trial, based on the hypothesis that tilapia would cover their nutritional requirements mostly by grazing the algae. Each feeding strategy was tested at two feeding levels. Mean daily feeding rate R in the progressive feeding strategy averaged 48.6 (low feeding level) and 102.5 kg ha?1 day?1 (high feeding level), and 49.8 and 82.9 kg ha?1 day?1 in the linear feeding strategy. Significantly better growth rates and feed conversion rates were obtained in the progressive feeding strategy. Average extrapolated net pond production was highest at Rpr=6% body weight day?1 (10.61 ha?1, year?1). It was concluded that cottonseed cake contributed to tilapia growth mainly directly as a tilapia feed rather than indirectly as a pond fertilizer via algal production. Finally, the appropriateness of the metabolic feeding rate Rmb(BW0.8 day?1) was discussed, compared with the progressive feeding rate Rpr (%BW day?1). (BW denotes body weight). A practical, two-step linear feeding method was proposed for cottonseed cake as a ‘rule of thumb’ that is workable in the field. |
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