Fermented soybean meal and soy protein concentrate had greater digestible energy but similar amino acid digestibility compared with soybean meal fed to weanling pigs

The objective was to determine energy concentrations and amino acid (AA) digestibility in soybean meal (SBM), 3 sources of fermented SBM (FSBM), and soy protein concentrate (SPC) fed to weanling pigs. In experiment 1, twelve barrows (initial body weight = 8.7 kg ± 0.5) were used to measure digestible energy and metabolizable energy (ME) in the soybean products in a replicated 6 × 4 incomplete Latin square design. A basal diet consisted of 969 g/kg corn as the sole energy source. Five experimental diets were formulated by replacing corn in the basal diet with SBM at 310 g/kg, FSBM-A at 270 g/kg, FSBM-B at 260 g/kg, FSBM-C at 290 g/kg, and SPC at 240 g/kg. In experiment 2, ten barrows (initial body weight = 10.5 kg ± 0.9) equipped with a T-cannula at the distal ileum were employed to determine standardized ileal digestibility (SID) of AA in a replicated 5 × 5 Latin square design. Five experimental diets contained SBM, 3 sources of FSBM, or SPC as the sole source of AA. The index method was employed for determining AA digestibility. The ME in FSBM-A and FSBM-B was greater (P < 0.05) compared with SBM but not different from the ME in FSBM-C or SPC. The SID of most AA in the 3 sources of FSBM was comparable to SBM or SPC. Overall, 2 of the FSBM sources had greater energy values compared with SBM but did not have different SID of AA compared with SBM or SPC.