Evaluation of elevated soybean meal diets with inclusion of exogenous enzymes on the effect of growth performance and digestibility

Authors: PHILLIPS, CAITLYN - Iowa State University; HUMPHREY, DALTON - Iowa State University; Trabue, Steven; BERGSTROM, JON - Dsm; GREINER, LAURA - Iowa State University

Submitted to: Translational Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/10/2026
Publication Date: 5/20/2026
Citation: Phillips, C., Humphrey, D., Trabue, S.L., Bergstrom, J., Greiner, L. 2026. Evaluation of elevated soybean meal diets with inclusion of exogenous enzymes on the effect of growth performance and digestibility. Translational Animal Science. https://doi.org/10.1093/tas/txag070.
DOI: https://doi.org/10.1093/tas/txag070

Interpretive Summary: Soybean meal (SBM) is a common protein source in pig diets but in large amounts it can lead to increased nitrogen, an important nutrient, loss. This study tested the effect of dietary enzymes, chemicals that help the pigs to break down and absorb the nutrients in food, on the digestion and retention of nutrients in pigs fed SBM. The results showed that feeding high levels of SBM did not harm pig growth, suggesting SBM can be used to replace synthetic amino acids. Enzymes did little to increase nutrient availability. These results will help researchers, feed companies, and growers to optimize nutrition with SBM to reduce production costs and increase farm profits.

Technical Abstract: Forty-eight crossbred gilts (52.55 ± 4.12 kg) were used to evaluate the effects of high soybean meal (SBM) inclusion with dietary enzymes on growth and nitrogen balance. Two replicates of 24 gilts were placed in metabolism stalls and randomly assigned to one of six dietary treatments (8 pigs/trt). After a common diet (d 0-12), experimental diets were fed in two phases (d 12-24 and 24-36). Urine and feces were collected for 72 h to assess nutrient digestibility and retention. Diets included: 1) negative control diet (NC, corn-soy + synthetic amino acids (AA)), 2) positive control diet, (PC, 41% SBM replacing synthetic lysine), 3) PC + xylanase (WX), 4) PC + multi-enzyme (VP, hemicellulase and pectinase), 5) PC + WX + VP (WXVP), and 6) PC + 1500 FTU/kg phytase (SD). All but SD contained 600 FTU/kg phytase. Data were analyzed as repeated measures in SAS 9.4 (Statistical Analysis System, Cary, NC) with treatment, phase, and block as fixed effects and pig served as the experimental unit. Growth did not differ across treatments (P > 0.13). Apparent total tract digestibility (ATTD) of DM and GE were unaffected (P = 0.10), but ash ATTD increased in high SBM diets (P < 0.01). Intake of nitrogen (N), phosphorus (P), calcium (Ca), and sulfur (S) increased with 41% SBM diets compared to NC (P < 0.01). Digestible N, P, Ca, and S were greater in 41% SBM diets (P < 0.01). Absolute N retention was higher in PC and SD and tended to be higher in VP and WXVP vs NC (P = 0.02). Retention of P was higher in PC, WX, VP, and SD vs NC (P < 0.01). Retention of Ca increased in all 41% SBM diets (P < 0.01). Retention of S was higher in PC, WX, VP, and SD vs NC, while NC and WXVP were similar (P = 0.02). Retention of N, P, and S as percent of intake or digestibility coefficients were similar (P = 0.26). Retention % of Ca intake trended higher in PC and SD vs NC (P = 0.06), and Ca retention % digestibility was greater in SD vs NC P = 0.05). Total N excretion was higher in WX, VP, and WXVP vs NC (P = 0.01). Total Ca excretion was higher in WXVP vs VP (P = 0.03). Total P and S excretion did not differ (P = 0.12). Digestible and metabolizable energy values were similar across treatments (P = 0.22). In conclusion, increasing SBM by 19% to meet lysine requirements had minimal impact on growth, but elevated nutrient intake, and retention, particularly N, P, Ca, and S. High SBM diets yielded higher N excretion vs NC regardless of enzyme inclusion.