A total of 4,730 pigs (PIC 337 × L 42) were used in a 20-d study to determine if caloric efficiency (CE) is an accurate predictor of soybean meal (SBM) net energy (NE) in nursery pigs. Pigs were blocked by sow source, entry date, and initial BW (initially 12.0 ± 0.39 kg) and allotted to one of 12 dietary treatments in a randomized complete block design. The twelve treatments were arranged in a 3 × 4 factorial with main effects of estimated SBM NE relative to corn in diet formulation (80, 100, or 120%) and SBM level (26, 30, 34, or 38%). The diet containing 26% SBM served as the base within each SBM NE level with fat being added or removed from the diet as SBM level increased depending on the assumed NE of SBM. There were 30 to 35 pigs per pen. There were 32 replications of the 26% SBM treatment and 12 replications of the remaining 9 treatments. Pigs were weighed and feed disappearance measured at the beginning and end of the study to determine ADG, ADFI, G:F, and CE. On d 21, following the growth study, a blood sample was collected from 5 pigs/pen (2 barrows and 3 gilts) to determine serum blood urea nitrogen (BUN). Pigs were fasted approximately 12 h prior to sample collection. To test SBM level × SBM NE interactions, the 30, 34, and 38% SBM level treatments were used. No SBM level × SBM NE interactions were observed. To test simple effects of SBM level within SBM NE, all four SBM level treatments were used. A quadratic effect of SBM level within the 80% SBM NE in formulation was observed (P < 0.05) where ADG and ADFI increased as SBM level increased from 26 to 34% but decreased as SBM level increased to 38%. A linear effect of SBM level was observed (P < 0.05) for G:F and serum BUN within all three formulation strategies, where G:F and serum BUN increased as SBM level increased. Caloric efficiency improved (linear, P < 0.001) with increasing SBM level within each of the formulation strategies (Figure 1). The increase in G:F appears to be a response to SBM level rather than SBM NE. Thus, the CE method may not be an accurate method of predicting SBM NE in nursery pigs.

Kim, T., P. Salgado-Lopez, J. Smallfield, M. Tokach, J. DeRouchey, J. Woodworth, R. Goodband, K. Gaffield, J. Gebhardt, H. Cemin, E. Hansen, M. Hart, J. Faccin and J. Soto. 2026. Is Caloric Efficiency an Accurate Method to Estimate Soybean Meal Net Energy in Nursery Pigs? ASAS Midwest Section Meeting. Abstract 19. https://doi.org/10.1093/jas/skag107.060

Read the research report about this work here: Kim, T., P. Salgado-Lopez, J. Smallfield, M. Tokach, J. DeRouchey, J. Woodworth, R. Goodband, K. Gaffield, J. Gebhardt, H. Cemin, E. Hansen, M. Hart, J. Faccin, and J. Soto. 2025. Is Caloric Efficiency an Accurate Method to Estimate Soybean Meal Net Energy in Nursery Pigs?. Kansas Agricultural Experiment Station Research Reports: Vol. 11: Iss. 7. https://doi.org/10.4148/2378-5977.8765.