Is Fortification of Methionine Necessary in Soya Bean (Glycine Max) Based Feeds for Oreochromis andersonii (Castelnau, 1861) Raised in Semi - Concrete Ponds?

Abstract

An experiment was conducted to determine the optimal amount of methionine that can be incorporated in the soya bean based Oreochromis andersonii feeds. Three levels (2%, 4% and 6%) of methionine included in soya bean based feed (30% and 10% crude protein and crude lipid respectively) were tested on O. andersonii for seventy eight (78) days in hapas erected in a semi–concrete pond (250 m2) arranged in a complete randomized design. Specific growth rate (SGR% day -1 ), mean body weight gain (MBWG) (g) and apparent feed conversion efficiency (AFCE %) differed (P 0.05) SGR (%), MBWG (g) and AFCE (%) but higher than the control and the lowest methionine level used in the experiment. Trend analysis showed a linear relationship (F=3.358, P=0.02) between Gonadosomatic Index (GSI) and methionine level with the highest methionine level producing fish with the highest GSI. Furthermore, the highest methionine level produced a significantly higher (P 0.05) in all the treatments. It is, therefore, recommended that soya bean based feed can be fortified with 4% methionine to improve the O.andersonii growth. An economic analysis is required to ascertain the cost effectiveness of using the synthetic amino acid in soya bean fish feeds for O. andersonii.