# Impacts of different dietary soybean meal levels on jejunal immunity of nursery pigs at different days post-weaning

## TL;DR

This study found that high soybean meal diets in young pigs increase gut inflammation and alter gut bacteria, with effects more pronounced shortly after weaning.

## Contribution

The study provides new insights into how soybean meal levels affect jejunal immunity in nursery pigs at different post-weaning stages.

## Key findings

- High SBM diets increased jejunal Prevotella abundance, IgA, crypt depth, and immune response in pigs.
- Pigs at 20 days post-weaning showed higher jejunal inflammation and intestinal damage compared to those at 42 days.
- High SBM diets consistently increased jejunal inflammation and reduced villus height to crypt depth ratio at both time points.

## Abstract

The objective of this study was to investigate the impacts of different dietary soybean meal (SBM) levels on jejunal immunity in nursery pigs at different days post-weaning.

Forty-eight pigs (6.2 ± 0.3 kg), weaned at 21 days of age, were assigned to 2 dietary treatments (n = 12) in a randomized complete block design and fed for 20 or 42 d in 3 phases (10, 10, and 22 d, respectively). The dietary treatments consisted of low and high SBM diets. On d 20 and 42, jejunal mucosa and tissue samples were collected. Treatments were arranged in 2 × 2 factors with dietary SBM levels (low and high SBM diets) and days post-weaning (20 d and 42 d post-weaning).

Pigs fed high SBM diets had greater (P < 0.05) relative abundance (RA) of jejunal Prevotella, tended to have greater (P = 0.091) jejunal IgA, had greater (P < 0.05) crypt depth, and tended to have lower (P = 0.064) villus height to crypt depth ratio (VH:CD) than pigs fed low SBM diets. Pigs at 20 d post-weaning had greater (P < 0.05) RA of jejunal Lactobacillus and had greater (P < 0.05) jejunal IL-8 and protein carbonyl than pigs at 42 d post-weaning. Pigs at 20 d post-weaning tended to have greater (P = 0.090) jejunal IgG, tended to have lower (P = 0.059) jejunal IgA, and had greater (P < 0.05) proportion (%) of Ki-67+ cells in the jejunal crypt than pigs at 42 d post-weaning.

Pigs fed high SBM diets showed greater RA of Staphylococcus, a greater immune response, and a decreased VH:CD in the jejunum than pigs fed low SBM diets. Pigs at 20 d post-weaning were more susceptible to jejunal inflammation and intestinal damage than pigs at 42 d post-weaning, but the negative impacts of high SBM diets on jejunal inflammation and intestinal damage were consistent compared to low SBM diets at 20 d and 42 d post-weaning.

The online version contains supplementary material available at 10.1186/s40104-025-01271-0.