Amino acid digestibility by weanling pigs of processed ingredients originating from soybeans, 00-rapeseeds, or a fermented mixture of plant ingredients

An experiment was conducted to determine the apparent ileal digestibility (AID) and the standardized ileal digestibility (SID) of CP and AA in 4 sources of processed soybean products, in conventional dehulled soybean meal (SBM-CV), in conventional 00-rapeseed expellers (RSE), and in a fermented coproduct mixture (FCM) that contained rapeseed meal, wheat, soy molasses, and potato peel fed to weanling pigs. The 4 processed soybean products included 2 sources of enzyme-treated soybean meal (ESBM-1 and ESBM2), extruded soybean meal, and soy protein concentrate (SPC). Twenty-seven weanling barrows (9.29 +/- 0.58 kg initial BW) were surgically equipped with a T-cannula in the distal ileum. Pigs were randomly allotted to three 9 x 5 Youden squares with 9 pigs and five 7-d periods in each square. Seven cornstarch-based diets were prepared using each of the protein sources as the sole source of CP and AA. A N-free diet was prepared to calculate basal endogenous losses of CP and AA, and this diet was fed to 2 groups of pigs, which resulted in a total of 9 dietary treatments. Results indicate that the SID of CP was greater (P < 0.05) in ESBM-1 than in SPC, RSE, or FCM. The SID of Arg, His, Ile, Leu, Met, and Phe were greater (P < 0.05) in ESBM-1 than in SPC, and the SID of Lys was greater (P < 0.05) in SBM-CV than in ESBM-2. The SID of Thr, Trp, Val, and total indispensable AA were not different among the soybean products, but the SID of total dispensable AA in ESBM-1 was greater (P < 0.05) than in SPC. Therefore, the SID of total AA was greater (P < 0.05) in ESBM-1 than in SPC, but no other differences were observed among soybean meal (SBM) products. The SID of most AA in RSE and the SID of all AA in FCM were less (P < 0.05) than in all the SBM products, but the SID of all AA in RSE were greater (P < 0.05) than in FCM. Results of this research indicate that although processing of SBM results in increased concentration of CP, processing may also reduce the digestibility of AA, which is likely due to heat damage during processing. There are, however, differences among processed soy products, with some products having greater SID of AA than others. Results also indicate that fermentation of a mixture of rapeseed meal, wheat, and relatively low quality coproducts does not result in SID values that are similar to those of unfermented 00-rapeseed expellers or soybean products.