EFFECTS OF HEAT PROCESSING ON DIGESTIBLE ENERGY AND OTHER NUTRIENT DIGESTIBILITIES OF FULL-FAT SOYBEANS FED TO WEANER, GROWER AND FINISHER PIGS

The influence of different heat treatments for full-fat soybeans (FFSB) on digestible energy (DE) values and fecal nutrient digestibilities was studied using 180 castrated male Landrace pigs at three different growth stages: weaner (17.1 +/- 0.2 kg), grower (32 +/- 0.2 kg) and finisher (61.6 +/- 0.3 kg). The soybean products used in weaner (30%), grower (25%) and finisher (20%) diets were soybean meal (SBM) or FFSB processed by either extrusion (Ex), jet sploding (Js), micronization (Mi) or roasting (Ro). Digestibilities were determined by total fecal collections during the last 7 d of each 12-d period. Dry matter (DM) and neutral detergent fiber (NDF) digestibilities of FFSB were lower (P < 0.05) in weaner than in grower or finisher pigs, but DE values and apparent digestibilities of crude protein (CP) and ether extract were not influenced by growth stage. Extruded FFSB had a superior CP digestibility than the other soybean products (86.4 vs. 79.8, 79.8, 80.0 and 78.2% for Js, Mi, Ro and SBM, respectively), and it also had a higher DE value (21.0 vs. 20.0, 19.6, 18.5 and 16.6 MJ DE kg-1 DM, P < 0.05). Extrusion of FFSB was most beneficial for weaner pigs as this heat treatment resulted in higher (P < 0.05) CP (87.8 vs. 80.9, 80.8, 82.1 and 76.6% for Js, Mi, Ro and SBM, respectively) and NDF (76.2 vs. 62.7, 63.3, 61.9 and 53.8% for Js, Mi, Ro and SBM, respectively) digestibilities. The heat treatments did not influence the CP and NDF digestibilities during grower or finisher stages. The data suggested that extrusion of FFSB yielded superior DE values and CP digestibilities than other heat treatments.