Effects of Various Heat Treatments on Concentrations of Digestible and Metabolizable Energy and on Amino Acid Digestibility in Soybean Meal Fed to Growing Pigs
Two experiments were conducted to determine DE and ME and standardized ileal digestibility (SID) of AA in heat-treated soybean meal (SBM) fed to growing pigs. The 9 treatments were prepared using a conventional SBM that was either not autoclaved or autoclaved following one of 8 treatments: 110°С for 15 or 30 min or 150°С for 3, 6, 9, 12, 15 or 18 min. In Exp. 1, 20 barrows (43.6 ± 2.2 kg) were assigned to a replicated 10 treatment × 4 period Youden square design. A corn-based basal diet and 9 diets containing corn and one of each SBM treatment were formulated. Urine and feces were collected for 5 d. In Exp. 2, 10 ileal-cannulated barrows (36.8 ± 1.2 kg) were allotted to a 10 treatment × 7 period Youden square design. A N-free diet and one diet for each of the 9 SBMs were used. Ileal digesta were collected on d 6 and 7 of each 7-d period. Orthogonal contrasts were used to compare effects among treatment temperatures and to determine linear effects of heating duration. There were no effects of autoclaving at 110°С on ME in SBM or on SID of AA in SBM, but both ME and SID of AA in SBM were less (P < 0.01) if SBM was autoclaved at 150°С compared with 110°С (Table 1). At 150°С, there were linear decreases (P < 0.01) in both ME and SID of AA in SBM as heating time increased. In conclusion, autoclaving at 110°С did not affect ME or SID of AA in SBM, but autoclaving at 150°С had negative effects on ME and SID of AA in SBM as heating time increased.