Chemical Composition and Digestibility of Processed Soybean Meal in Clarias Gariepinus, Burchell, 1822

Abstract

Abstract

Effect of solvent extraction and roasting on chemical composition and digestibility of soybean based diet by Clarias gariepinus was assessed in this study. Raw soybean grains (9kg) were milled to pass through 2mm mesh size. The milled raw soybeans were divided into three equal portions. A portion was used raw as test ingredient. The second portion was roasted for 15 o minutes at 110 C while the third portion was soaked in 3000 mL of n-hexane for 12 hours to extract oil. Processed soybean was used to formulate diets for Clarias gariepinus to assess its apparent and true digestibility. Clarias gariepinus (n=180) weighing 17.74±0.29g were randomly allotted to three treatments each in triplicates of twenty fish. The design of the experiment was completely randomized design. Processing significantly increased (P<0.05) crude protein (%) from 46.01±0.06 in raw soybean to 58.45±2.50 in solvent extracted soybean and 52.50±2.78 in roasted sample. Significantly higher (P<0.05) ether extract (%) and -1 metabolizable energy (kcal/g ) were obtained in raw soybean (19.20±0.10 and 4.13±0.03) than in solvent extracted soybean meal (8.09±0.02 and 3.74±0.04), respectively. Also, lysine and methionine were significantly higher (P<0.05) in solvent extracted soybean meal, closely followed by raw soybean and least in roasted soybean meal. Trypsin inhibitor activity was highest (P<0.05) in raw soybean and least in solvent extracted soybean meal. Apparent digestibility of dry matter, crude protein, crude fibre, nitrogen free extract and ether extract by C. gariepinus were significantly higher (P<0.05) in solvent extracted soybean based diet compared with roasted soybean based diet. Processing enhanced the digestibility and nutritional potential of solvent extracted and roasted soybean meal for Clarias gariepinus.