Abstract This study aimed to validate a recent net energy (NE) estimate for soybean meal (SBM; 2,517 kcal/kg) using two concurrent grow-finish assays conducted under controlled university and commercial conditions in a fixed-weight harvest strategy. In the university study, 240 pigs (PIC 337 × Camborough; 29.1 ± 0.56 kg BW) were assigned across 60 pens for 96 days, divided into four dietary phases. In the commercial study, 1,200 pigs (PIC 800 × Camborough; 26.7 ± 0.45 kg BW) were housed across 60 pens and fed for 110 days following the same four-phase feeding program. Within dietary phases, diets were formulated to be isocaloric based on NE, to contain the same SID Lysine to energy ratio, and to meet or exceed amino acid and nutrient requirements. Diets were corn-SBM-based with soybean oil to balance dietary NE. Increasing SBM levels for Phase-1 included 26, 30, 33, 36, and 39%; Phase-2, 19, 22, 25, 28, and 31%; Phase-3, 15, 17, 20, 22, and 25%; and Phase-4, 15, 16, 18, 19, and 20%. The same SBM source was used in both studies. In Phase 3 of the university study, two replicates of 24 pigs were sampled from the growth assay, placed in metabolism crates for a 5-day acclimation, and subjected to a 3-day total fecal collection. Data were analyzed as a randomized complete block design with pen as the experimental unit. Pigs in both studies had a similar health status and were all positive for PRRS. In the University study, increasing SBM inclusion reduced Phase-1 ADFI (linear P = 0.04; 1.87, 1.78, 1.81, 1.77, 1.74 kg/d), G:F (linear, P 0.01; 479, 508, 487, 507, 512 g/kg) and caloric efficiency (NE:gain) improved as SBM increased (linear, P 0.01; 5264, 4962, 5191, 4969, 4929 kcal/kg of gain). However, increasing SBM inclusion did not impact overall G:F (P = 0.770), ADG (P = 0.680), ADFI (P = 0.973), real-time ultrasound backfat thickness (P = 0.176), loin depth (P = 0.808), carcass backfat thickness (P = 0.965), loin depth (P = 0.357), and hot carcass weight (P = 0.160). Increasing SBM inclusion had no impact on the apparent total tract digestibility of energy (P = 0.930) or the metabolizable energy (P = 0.940). Under commercial conditions, SBM inclusions improved Phase-1 G:F (linear, P = 0.010; 509, 513, 518, 518, 521 g/kg) and NE:gain (linear, P = 0.010; 4941, 4892, 4845, 4889, 4843 kcal/kg of gain). Overall, ADG (P = 0.451), ADFI (P = 0.632), and G:F (P = 0.497) were unaffected, and no differences were found in body composition through ultrasound or carcass measurements (P ≥ 0.05). In conclusion, findings from both the University and Commercial studies demonstrated that the recent SBM NE estimate of 2,517 kcal/kg is accurate in both conditions based on growth performance and body composition. However, phase-1 results for feed and caloric efficiency in both studies suggest that the NE may be underestimated.
Lima et al. (Wed,) studied this question.