A study was conducted to determine the standardized ileal digestibility (SID) of amino acids (AA) and to calculate net energy (NE) for micronized regular full-fat soybean (R-FFSB) and low stachyose and raffinose full-fat soybean (LSR-FFSB) for growing pigs. Six ileal-cannulated barrows weighing 31.4 kg were fed six diets in a 6 × 6 Latin square. The six diets were cornstarch-based with soybean meal (SBM), R-FFSB, LSRFFSB, or lentil as the sole source of protein; N-free diet (NFD); and enzymatically hydrolyzed casein diet (EHC). Energy digestibility in SBM, R-FFSB and LSR-FFSB was determined difference from the NFD and the SID of AA for SBM and test ingredients was calculated using NFD or EHC.
Results indicated that the SID of AA for feedstuffs was similar between two methods (NFD vs. EHC). The SID of lysine for SBM (93%) was higher (P < 0.05) than that for R-FFSB or LSR-FFSB, which were similar in SID of lysine (76 vs. 79%). The SID of other indispensable AA for SBM was also higher (P < 0.05) than that for R-FFSB or LSR-FFSB, which were similar in SID of the same AA.
The NE value for SBM was estimated to be 2.62 Mcal/kg of DM. However, SBM had lower (P < 0.05) NE content than R-FFSB or LSR-FFSB, which were similar in NE content (2.96 vs. 3.07 Mcal/kg of DM). The researchers concluded that FFSB (regular vs. LSR) may not affect the NE and SID of AA for micronized FFSB fed to pigs. Micronized FFSB (regardless of seed characteristic) is a better source of dietary energy, but not AA compared to SBM.