The aim of this study was to characterize ruminal degradation and postruminal digestibility of dry matter (DM) and crude protein (CP) in full-fat raw soybeans (ffSB), extruded full-fat raw soybeans (effSB) and soybean cake (SBc) derived from three non-GMO locally grown soybean varieties (PETRINA, ERICA and VIOLA). To hasten data interpretation, ruminal degradation and postruminal digestibility of the conventional solvent-extracted soybean meal (SBM) was also investigated. Effective rumen degradation (ERD) of DM was lower for SBc (0.726) than for SBM (0.777; p < 0.001). Independent of soy variety, it was less for SBc than ffSB (0.801) and the least for effSB (0.783; p < 0.001). Intestinal DM digestibility was higher for SBM (0.946) compared to ffSB (0.708) and effSB (0.604), and regardless of soybean variety, it was lower for effSB than for SBc (0.866; p < 0.01). The ERD of CP was higher for ffSB (0.817) compared to SBM (0.6858; p = 0.007), and, independent of soy variety, it was less for SBC (0.773) than ffSB and the lowest for effSB (0.750; p < 0.001). Intestinal digestibility of CP was higher for SBM (0.998) compared to ffSB (0.944), effSB (0.926), and SBc (0.943). Regardless of soybean variety, it was lower for effSB than for ffSB and SBc (p < 0.002). However, interactions between product type and soybean variety were also detected for almost all investigated parameters, except for c for DM and c and ERD for CP (p < 0.001), with variety ERICA showing the lowest ERD and variety PETRINA showing the highest intestinal digestibility. The study demonstrated that the type of soybean processing and soybean variety significantly affected ERD and intestinal digestibility of DM and CP. Soy products (effSB and SBc) produced by the farmer on his own farm from non-GMO soybeans harvested on his own farm can serve as valuable feed material for cattle, making him independent from the need to purchase imported SBM.
Śliwiński et al. (Sat,) studied this question.