Nutritive value and availability of commonly used feed ingredients for farmed Nile tilapia (Oreochromis Niloticus l.) and African catfish (Clarias gariepinus, burchell) in Kenya, Rwanda and Tanzania

Abstract

Commonly utilized feed ingredients for culture of Nile tilapia (Oreochromis niloticus) and African catfish (Clarias gariepinus) from Kenya, Tanzania and Rwanda were collected over a period of six months (January - June 2010) and evaluated for their nutritive composition through proximate analysis. Most of the fish feed ingredients were found in all the three countries except a few that were unique to one or two countries as detailed in the results. Feed ingredients of animal origin exhibited significantly (P<0.05) higher crude protein levels (407 - 635 g/kg DM) compared to the feed ingredients of plant based origin. Freshwater shrimps (Caridina nilotica) contained the highest crude protein levels of 635 g/kg DM. Feed ingredients of animal origin had low ether extracts (EE) with an exception of Omena fish (Rastrineobola argentea). Crude fibre (CF) was generally higher on feed ingredients of plant origin and ranged between 55- 368 g/kg DM while Nitrogen Free Extracts (NfE) and ash content were higher in the feedstuffs of plant origin with an exception of maize bran which had the lowest value. Omena fish and freshwater shrimp had higher ash content of 182 and 228g/kg DM compared to other feed ingredients of animal origin, which may indicate contamination with soil particles during drying process. Based on the feed ingredient availability, potential competition with other human uses, content of crude protein and crude fibre and the feasibility of removal of anti-nutritional factors, C. nilotica, blood meal, meat and bone meal, were identified as most promising sources of animal based protein. Cotton (Gossypium spp) and sunflower (Helianthus annuus) seed cakes provided the best option as source of processed plant based protein. Leaves of gallant soldier (Galisonga parviflora), sweet potato (Ipomoea batatus), cassava (Manihot esculenta) and papaya (Papaya carica) were identified as high potential feedstuffs of plant origin either processed or in raw form for small-scale fish farming. We recommend that in well fertilized semiintensive ponds, maize (Zea mays), wheat (Triticum aestivum) and rice (Oryza sativa) bran may be utilized where available to supplement natural pond food.