Extrusion is a thermomechanical process that can reduce the content antinutritional factors in soybean, improving the use of its nutrients by pigs. The purpose of this study was to evaluate extruded corn-soybean grain blends, replacing soybean meal in weanling pig diets, on pigs growth performance from 21 to 63 d old. Ground corn and the corn-soybean blend (75.27% of ground corn and 24.73%) were extruded at 120°C in a single-screw extruder. One hundred and sixty crossbred weaned pigs (6.02 ± 0.63 kg) were used in a three-phase feeding program (21-35, 36-49, 50-63 days of age) and fed a basal diet (BD – extruded corn, dairy product, spray dried plasma, and soybean meal) or one of four diets in which soybean meal was replaced for deactivated (DS) or extruded (EX) corn-soybean blend, in 50 or 100%, generating diets DS50, DS100, EX50 and EX100. Diets were formulated to provide 3.40, 3.38, and 3.20 Mcal of ME/kg; 220, 215, and 190 g/kg of CP; and 14.5, 13.3, and 10.9 g/kg of digestible lysine, in phases 1, 2, and 3, respectively. A randomized block design based on initial BW was used. The data was submitted to ANOVA and means were separated using Tukey test (5%). Pigs fed diets EX50 and EX100 presented reductions (P< 0.05) in ADG (16-50%), final BW and G:F (13-33%) compared to pigs submitted to diets SBM100, DS50 or DS100 in phases 1 and 2. ADG, ADFI, and G:F of pigs were not affected (P >0.05) in phase 3, but final BW of pigs fed extruded corn-soybean blend were lower (P< 0.05) than that of pigs fed other diets.
The extrusion temperature may have been insufficient to inactivate the anti-nutritional factors of soybean that probably reduced pigs growth performance The inclusion of extruded corn-soybean blend in replacement of soybean meal reduced growth performance of pigs.