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Apparent digestibility of soybean coproducts in extruded diets for Nile Tilapia, Oreochromis niloticus

Vidal, L.V.O., Xavier, T.O., de Moura, L.B., Graciano, T.S., Martins, E.N., Furuya, W.M.
Aquaculture nutrition 2017 v.23 no.2 pp. 228-235
Oreochromis niloticus, amino acid composition, aquaculture, chromic oxide, coproducts, crude protein, digestibility, energy, experimental diets, histidine, ingredients, juveniles, limiting amino acids, methionine, nutritive value, protein concentrates, protein sources, rearing, soy protein, soybean meal, soybeans, valine
Soybean coproducts are important protein sources in aquaculture because of their amino acid profile. Tilapia can be reared on soybean coproducts as the only source of dietary protein without compromising growth. This study estimated apparent digestibility coefficients for five soybean coproducts for juvenile Nile tilapia, Oreochromis niloticus, fed with extruded diets. A reference diet and test diets consisting of 70% reference diet and 30% coproduct ingredient were formulated, along with 5.0 g kg⁻¹ chromic oxide (Cr₂O₃) as a marker. Apparent digestibility coefficients (ADC) for dry matter (ADCDM), gross energy (ADCGE) and crude protein (ADCCP) for soybean coproducts were estimated as 84.2–88.4%, 86.9–91.1% and 96.8–97.9%, respectively. ADCDM and ADCCP values did not vary among the ingredients, but low‐protein soybean meal exhibited lower ADCGE values than did soybean protein concentrate. ADCs of all amino acids were >95%, and mean ADCs for amino acids were similar to the values observed for ADCCP. Soybean coproducts had good nutritional value in extruded diets fed to tilapia. Methionine, histidine and valine were the limiting amino acids in all evaluated ingredients.