Effects of differently processed soybean substituted diets on nutrient utilization and the growth perormance of <i>Clarias gariepinus</i> juveniles

Abstract

Growth and nutrient studies was carried out on Clarias gariepinus Juveniles of mean weight 7.00-8.00g stocked into rectangular plastic aquarium tanks 30cm x 15cm for 120 days fed with differently processed soya bean meal. There were eight  treatments labeled as diet T₁-T₈, diet T₁ (control diet; contains no soybean meal but has fishmeal as the protein source); diet T₂ (Conventional diet; purchased  commercially); diet T₃ (contains a partial replacement of fishmeal with raw soybean meal at 66.7 replacement) diet T₄ (has 100% of raw soybean meal inclusion), diet T₅ (66.7% toasted soybean inclusion); diet T₆ (100% toasted soybean inclusion); diet T₇ (100% raw soybean with methionine and lysine); diet T₈ (100% toasted  soybean with methionine and lysine). The diets were formulated at 40% crude  protein containing soya bean meal at different inclusion rates; the toasted soya bean was toasted at 100^oC for 10 minutes using an oven and then milled into a fine powder before being mixed with other ingredients. Results showed that the highest average weight gain of 432.55g, specific growth rate (SGR) of 3.38% and food conversion ratio (FCR) of 5.78 of the formulated diets respectively were recorded in fish fed with diet T₅ (toasted soyabean meal) P<0.05. The Juveniles fed raw soybean gave the least growth performance (Diet T₃) and (Diet T₄) P>0.05. this relative lower growth performance of the fish might be attributed to the presence of higher levels of anti-nutritional factors present in soybeans for example trypsin inhibitors and phytic acid which may interfere with the availability of nutrients to the fish; from the result It could be concluded in practice that toasted soybean based diet is optimal for growth of Clarias gariepinus Juvenile. Mortality rates recorded during the dietary trial ranged between 30% in fish fed diet T₈ to 100% in the remaining diets. The results were discussed in relation to fish feed production and its implication for fish culture intensification in Nigeria and it is recommended that toasted soya bean should be embraced as the most preferred treatment for the soyabean used in fish feed

Keywords: Processed soya bean, fishmeal, growth Juveniles, Clarias gariepinus