Abstract Dietary soybean meal (SBM) content has been reported to be positively associated with improved growth and feed conversion efficiency (van Heugten, 2024). This study was conducted to determine whether growth could be improved by feeding higher levels of SBM than are typically fed. This study examined that finding with a total of 95,213 pigs (6.0 ± 0.1 kg; PIC 800 sired, Hendersonville, TN) of high-health status (derived from 3 PRRSv negative or stable sow farms) from weaning to harvest (158 ± 0.1 d). Pigs were placed in 41 2,400-head wean-to-finish barns that were alternated to 1 of 2 treatments (control treatment or a high SBM treatment HSBM) in a rolling allotment over 7-months. Dietary treatments were formulated to be nutritionally equivalent. The net energy (NE) value of SBM for HSBM diets was set equal to corn (2,624 ± 24 kcal/kg). The calculated NE of SBM for the control treatment was 2,099 ± 27 kcal/kg. Control pigs fed typical diets consumed 56.5% less SBM from wean-to-harvest compared to those fed HSBM diets (control = 35.4 vs. HSBM = 62.6 kg; P 0.001). Conversely, control pigs consumed 53.8% more DDGS than HSBM pigs (control = 54.3 vs. HSBM = 35.3 kg; P 0.001). Throughout the experiment, diets were reformulated to maximize return over feed costs within constraints of SBM, DDGS, and crystalline lysine for both control and HSBM diets. Data were analyzed as a completely randomized design for ANCOVA, using the lm function in R with barn as the experimental unit, treatment as the main effect, and days on feed as a covariate. Total feed consumption was similar for control and HSBM pigs (332.0 vs. 330.5 kg, respectively; P = 0.85) as was ADFI (2.10 vs 2.10 kg/d; P = 0.87) for the 158-d test. Total feed consumed reflects constant days on feed but not constant harvest weight (control = 131.3 vs. HSBM = 132.6 kg; P = 0.18). Compared to the control, pigs fed HSBM diets tended to improve ADG (control = 0.789 vs. HSBM = 0.803 g/d; P = 0.07) and percent carcass lean (control = 56.9 vs. HSBM = 57.1%; P = 0.07). Gain:feed ratio (control = 0.378 vs. HSBM = 0.383; P = 0.41), mortality (control = 5.4 vs. HSBM = 5.3%; P = 0.97), grade 1 market pigs (control = 92.8 vs. HSBM = 92.6%; P = 0.81), carcass yield (75.3 vs 75.1%, P = 0.42) and carcass weight variance (P = 0.87) were similar. In conclusion, increasing SBM tended to increase growth rate and carcass lean, without affecting carcass yield. Pig viability was not different, but the absence of respiratory disease minimized the opportunity for differentiation. These results support NE 80% of corn.
Kellner et al. (Wed,) studied this question.