Nutritive value of extruded or multi-enzyme supplemented cold-pressed soybean cake for pigs

The objectives were to determine the standardized ileal digestibility (SID) of AA and NE value of cold-pressed soybean cake (CP-SBC), and the effect of extrusion or adding multi-enzyme to CP-SBC diet for growing pigs. Eight ileal-cannulated pigs (initial BW = 79.7 ± 3.97 kg) were fed 4 diets in a replicated 4 × 4 Latin square design to give 8 replicates per diet. Diets included a cornstarch-based diet with CP-SBC, extruded CP-SBC, and SBC plus multi-enzyme (1,200 U of xylanase, 150 U of glucanase, 500 U of cellulase, 60 U of mannanase, 700 U of invertase, 5,000 U of protease, and 12,000 U of amylase/kilogram of diet; Superzyme-CS, 0.5 g/kg); and a N-free diet. The CP-SBC was the sole source of protein in the CP-SBC-containing diets. The ratio of cornstarch to sugar and soybean oil in CP-SBC-containing diets was identical to the N-free diet to allow calculation of energy digestibility of CP-SBC by the difference method. The evaluated CP-SBC had been produced by heating the soybean seed at 105°C for 60 min followed by pressing of the heated soybean seeds at less than 42°C (barrel temperature). On a DM basis, CP-SBC and extruded CP-SBC contained 47.8 and 47.1% CP, 15.6 and 10.5% ADF, 7.23 and 8.85% ether extract, 3.11 and 3.08% Lys, and 2.25 and 3.70 trypsin inhibitor units per mg, respectively. Extrusion increased ( < 0.001) the SID of AA for the CP-SBC by an average of 12%. Also, extrusion increased ( < 0.001) the NE value of the CP-SBC from 2,743 to 2,853 kcal/kg of DM. Supplementation of CP-SBC diet with the multi-enzyme increased ( < 0.05) the SID of Arg and Pro, and tended to increase ( < 0.1) the SID of Ile and Tyr. However, the multi-enzyme supplementation did not affect the NE value of CP-SBC. In conclusion, the CP-SBC evaluated in the present study could be an alternative source of AA and energy in swine diets, and its nutritive value can be increased by extrusion following cold-pressing. The multi-enzyme used in this study improved the digestibility of some AA, but had limited effect on energy digestibility and hence NE value of the CP-SBC.