Allergenic soy proteins have shown to cause intestinal immune challenges to nursery pigs and small pigs may undergo increased challenged due to their immature intestine. Fermentation process breaks down allergenic proteins but it is not clear if the active sites are entirely hydrolyzed. This study aimed to evaluate the impacts of different types of fermented soybean meal (FSBM) replacing animal protein supplements on jejunal immune challenge and growth of nursery pigs with different BW at weaning. Thirty-six newly weaned pigs were grouped by their initial BW (6.2 ± 0.2 kg and 7.0 ± 0.3 kg) and allotted to three dietary treatments: a control diet containing animal protein supplements and diets replacing animal protein supplements with SBM fermented with either Lactobacillus (FSBML) or Bacillus (FSBMB). Therefore, treatments were arranged in 2 × 3 factors with BW and diets as two factors. Pigs were fed for 39 d in 3 phases (7, 13, and 19 d, respectively). On d 39, pigs were euthanized to collect jejunal mucosa and tissues to evaluate jejunal immune challenges. Jejunal protein carbonyl in pigs with low-BW group tended to be greater (P = 0.075) compared with high-BW group. Jejunal tumor necrosis factor-alpha in pigs fed FSBML diet was greater (P < 0.05) than control diet regardless of initial BW at weaning. Jejunal interleukin-8 (IL-8) in pigs fed FSBML diet tended to be greater (P = 0.054) compared with pigs fed FSBMB diet in the low-BW group, whereas jejunal IL-8 was not different between pigs fed FSBML and FSBMB diets in the high-BW group. Pigs fed with FSBM replacing animal protein supplements increased (P < 0.05) ileal digestibility of crude protein compared with the control diet. Pigs fed FSBML diet tended to decrease average daily gain in phase 1 (P = 0.061) and overall (P = 0.081), tended to decrease average daily feed intake in phase 1 (P = 0.069). In conclusion, replacing animal protein supplements by FSBML caused the reduced growth performance of nursery pigs, which might be due to increased inflammation in the jejunum, particularly in pigs with low BW at weaning. However, the use of FSBMB replacing animal protein supplements in nursery diets did not affect overall growth performance and intestinal health of pigs regardless of BW at weaning.

Sung, J., S. Kim and Z. Deng. 2025. Effects of fermented soybean meal replacing animal protein supplements on jejunal immune challenge and growth of nursery pigs with different body weight at weaning. 2025 American Society of Animal Science Midwest Section meeting, Abstract 19.