Evaluating the Metabolizable Energy of Ultra-high Protein, Low Oligosaccharide, Soybean Meal in Growing Pigs

Soybean meal (SBM) is used as the primary protein source in conventional swine diets due to its favorable amino acid profile and high protein concentration. Recent advancements in plant breeding and genetic selection have led to the development of Ultra-High Protein, Low-Oligosaccharide soybean varieties (UHP-LO) resulting in soybean meal with lower antinutritional factors. The experimental objective was to evaluate the metabolizable energy (ME) of diets in grower pigs fed either conventional SBM or UHP-LO SBM. A total of 30 barrows were selected (BW = 43.0 ± 4.5 kg) and randomly assigned to one of three dietary treatments: a corn control diet containing no soybean meal, a diet containing 28% conventional SBM, or a diet containing 28% UHP-LO. Pigs were housed individually in metabolism crates for a 10-day dietary adaptation period and a 4-day total collection period of feces and urine (96-hours). Pigs were limit-fed at 2.4 times maintenance energy split into two equal meals per day. Feces and urine were collected for total energy balance with marker-to-marker method using TiO2 and the apparent total tract digestibility (ATTD) of nutrients were calculated. Data were analyzed using a linear mixed model with treatment as a fixed effect, crate type as random effect, and initial BW as a covariate where appropriate. Ultra-high protein, low oligosaccharide SBM increased ATTD of dry matter by 1.52% (P = 0.012) and gross energy by 1.04% (P < 0.001), but did not alter ATTD of CP (P > 0.1) compared with SBM-CONV. Compared to control and SBM-CONV, diet DE kcal/kg of DM and diet ME kcal/kg of DM increased in the UHP-LO diet (P < 0.001), indicating more digestible and metabolizable energy per unit of dry matter in UHP-LO. However, in comparison to the corn control, DE:ME decreased by 2.21% in the SBM-CONV diet, and by 2.95% in the UHP-LO diet, indicating increased urinary losses with the high protein ingredient. The calculated digestible energy (DE) and metabolizable energy (ME) of UHP-LO were 3723 and 3507 kcal/kg on a DM basis. Overall, inclusion of UHP-LO soybean meal increased energy utilization efficiency in grower pigs, providing 2.9% more digestible and 2.8% more metabolizable energy than conventional SBM.