A total of 360 barrows (DNA 200 × 400; initially 6.1 ± 0.03 kg) were used in a 42-d trial to evaluate the effects of increasing trypsin inhibitor on nursery pig growth performance, fecal dry matter (DM) and nutrient digestibility. At weaning, pigs were randomly assigned to pens with five pigs per pen and 12 pens per treatment. There were six dietary treatments formulated to provide 1.4, 2.1, 2.8, 3.5, 4.2, and 4.9 trypsin inhibitor units (TIU)/mg of complete feed. Soy flour (76 TIU/mg) was added at the expense of soybean meal (5 TIU/mg) to create the treatment TIU levels. Diet formulation was based on analyzed nutrient values of the soy flour and soybean meal, assuming digestibility coefficients for soy flour were equivalent to those of soybean meal. Experimental diets were fed in three phases: phase 1 from d 0 to 10, phase 2 from d 10 to 24, and phase 3 from d 24 to 42. Feces were collected from three pigs per pen on d 10 and 42 to determine fecal DM, and d 42 fecal samples were used to determine apparent total tract digestibility (ATTD) of DM and crude protein (CP). Across all three individual dietary phases and overall (d 0 to 42), increasing TIU decreased (linear,P < 0.001) ADG, ADFI, and G:F. Fecal DM on d 10 increased (linear, P < 0.05; quadratic, P = 0.088) as TIU increased, with the majority of increase in fecal DM being observed as trypsin inhibitor increased from 3.5 to 4.9 TIU/mg of complete feed. However, there were no differences in fecal DM on d 42. The ATTD of DM decreased then increased (quadratic, P = 0.003) as TIU increased in the diet with the lowest ATTD of DM occurring at 4.2 TIU/mg of complete feed. Furthermore, the ATTD of CP decreased (linear, P < 0.001) as the level of TIU/mg of complete feed increased. In conclusion, these data suggest that increasing dietary TIU above 1.4 TIU/mg of complete feed reduces nursery pig growth performance and ATTD of nutrients.

Collier, S., P. Soper, K. Gaffield, R. Goodband, M. Tokach, J. Woodworth, J. DeRouchey, J. Gebhardt and H. Krishnan. 2026. Evaluation of Increasing Trypsin Inhibitor on Nursery Pig Growth Performance, Fecal Dry Matter, and Nutrient Digestibility. ASAS Midwest Section Meeting. Abstract 68. https://doi.org/10.1093/jas/skag107.043

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Read the research report for this work here: Collier, S., P. Soper, K. Gaffield, R. Goodband, M. Tokach, J. Woodworth, J. DeRouchey, H. Krishnan and J. Gebhardt. 2025. Evaluation of Increasing Trypsin Inhibitor on Nursery Pig Growth Performance, Fecal Dry Matter, and Nutrient Digestibility. Kansas Agricultural Experiment Station Research Reports: Vol. 11: Iss. 7. https://doi.org/10.4148/2378-5977.8743.