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.

1110°С vs. 150°С: P < 0.001. 2Linear effect of heating time at 150°С: P < 0.001.