Digestible and metabolizable energy in soybean meal and soybean hulls when fed to growing pigs or sows.

An experiment was conducted to test the hypothesis that the apparent total tract digestibility (ATTD) of gross energy (GE) and concentrations of digestible energy (DE) in soybean meal (SBM) and soybean hulls are greater when fed to gestating sows or lactating sows than to growing pigs, and that there is no difference in ATTD of GE between gestating and lactating sows. Three experimental diets were prepared. The basal diet consisted of corn as the sole source of energy, and two additional diets contained corn and 30% SBM or corn and 20% soybean hulls. All diets were fed to growing pigs and gestating and lactating sows. Twenty-four growing pigs and twenty-four gestating sows were housed in metabolism crates, and fecal and urine samples were quantitatively collected. Twenty-four lactating sows were housed in farrowing crates and feces were grab-sampled. The ATTD of GE, DE, and metabolizable energy (ME) were calculated in diets fed to growing pigs and gestating sows, and DE and ME in SBM and soybean hulls were calculated as well. The ATTD of GE and DE were also determined in diets fed to lactating sows, and DE was determined for SBM and soybean hulls. Results from growing pigs indicated that DE and ME were greater (P < 0.05) in corn and SBM compared with soybean hulls. For gestating sows, DE in corn and SBM was also greater (P < 0.05) than in soybean hulls, and ME in corn was greater (P < 0.05) than in SBM, whereas soybean hulls had the least (P < 0.05) ME. Results for lactating sows indicated that DE in corn and SBM was greater (P < 0.05) than in soybean hulls, but lactating sows had greater (P < 0.05) DE for soybean hulls than gestating sows and growign pigs, whereas gestating sows had greater (P < 0.05) DE for corn than lactating sows. Gestating sows also had greater (P < 0.05) ME for corn than growing pigs whereas growing pigs had greater (P < 0.05) ME for SBM than gestating sows. In conclusion, soybean hulls contain less DE and ME than corn and SBM, but there are no consistent differences in DE and ME among growing pigs, gestating, and lactating sows.