Abstract

Considering price as the main limiting factor in the use of animal proteins, this study evaluated the protein quality of diets for Nile tilapia containing oilseed meals as replacements of fishmeal. A control diet (FMBD) (30% crude protein and 2900 Kcal DE/kg) was formulated using fishmeal (FM), soybean meal (SBM), canola meal (CM) and sunflower meal (SFM). The test diets SBBD, CMBD and SFBD were formulated by replacing 10% CP of FM by SBM, CM and SFM, respectively. The amino acid profile was determined by MPA FT-NIR spectrometer (Bruker, Germany). Fishmeal recorded higher levels (p < 0.05) of lysine (7.81 mg/100 g), methionine (2.89 mg/100 g), arginine (5.87 mg/100 g), threonine (4.28 mg/100 g) and isoleucine (4.55 mg/100 g). The chemical score for all essential amino acid in fishmeal were higher than 100. Sunflower meal was a superior (p < 0.05) protein source with an essential amino acid index (EAAI) of 1.14 compared to CM (0.80) and SBM (0.70). Substituting FM with SBM, CM or SFM, reduced (p < 0.05) the levels of all amino acids apart from methionine which was increased (p < 0.05) in the diet with SBM substitute. In all diets, methionine and isoleucine were the first and second limiting amino acids, respectively. Though the diet containing FM exhibited higher (p < 0.05) EAAI (0.97), it was not satisfactory because it was limiting in methionine. The EAAI reduced (p < 0.05) with replacement of fishmeal by SBM (0.78), CM (0.77) and SFM (0.76). The study showed that the control diet had good quality protein and substitution with SBM, CM and SFM gave useful protein diets.

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