# Moderate Reduction in Dietary Net Energy Level Enhances Intestinal Health in Tunchang Pigs via Gut Microbiota Modulation

## TL;DR

Reducing the energy in pig feed slightly improves their gut health by changing gut bacteria and increasing helpful fatty acids.

## Contribution

This study shows that moderate reductions in dietary energy improve intestinal health in pigs through gut microbiota modulation and SCFA production.

## Key findings

- A 9.32 MJ/kg diet increased jejunal villus height and improved intestinal barrier function in pigs.
- The diet reduced inflammation and boosted antioxidant enzyme activity in the gut.
- Beneficial bacteria and short-chain fatty acid levels were elevated with the low-energy diet.

## Abstract

Energy constitutes a substantial portion of feed costs, and rising prices are driving producers to optimize feed management through precise dietary formulations. However, research on the effects of low net-energy diets on the intestinal health of finishing pigs remains limited, particularly with respect to the underlying regulatory mechanisms. This study investigated the effects of low net-energy diets on the intestinal health of Tunchang pigs. Compared with the control group, a diet with a net energy level of 9.32 MJ/kg increased jejunal villus height and the villus-height-to-crypt-depth ratio, while enhancing intestinal barrier function by upregulating the expression of tight junction protein genes. Additionally, the 9.32 MJ/kg diet improved intestinal antioxidant and anti-inflammatory functions by boosting the activity of antioxidant enzymes and reducing the expression of pro-inflammatory cytokine genes. Furthermore, this diet increased the abundance of beneficial bacteria and elevated short-chain fatty acid (SCFA) levels. In conclusion, a moderate reduction in dietary net energy (by no more than 0.5 MJ/kg) improved intestinal barrier function, antioxidant capacity, and anti-inflammatory response by modulating the gut microbiota and enhancing SCFA production. This study provides a theoretical basis for the application of low net-energy diets in finishing pig production.

To investigate the effects of low net-energy (NE) diets on intestinal health in Tunchang pigs, 96 animals (25.40 ± 1.11 kg) were randomly assigned to four dietary treatment groups with NE levels of 9.82 (CG), 9.57 (EY1), 9.32 (EY2), and 9.07 (EY3) MJ/kg. Each group consisted of six replicates with four pigs per replicate. The experiment lasted for 63 days. The results showed that compared with the CG, the EY2 increased jejunal villus height and villus height-to-crypt depth ratio, as well as reduced crypt depth in the colon (p < 0.05). Both the EY1 and EY2 demonstrated improved intestinal barrier function through upregulation of zonula occludens-1 and occludin expression in the jejunum, zonula occludens-1 in the ileum, and zonula occludens-1, occludin, and claudin-1 in the colon (p < 0.05). Furthermore, EY2 significantly increased the activities of superoxide dismutase, glutathione peroxidase, and catalase, while reducing malondialdehyde content in both the jejunum and colon (p < 0.05). EY2 showed significantly downregulated relative expression of pro-inflammatory cytokines, including interleukin-1β, tumor necrosis factor-α, and interleukin-6, in the jejunum, ileum, and colon (p < 0.05). Microbial and short-chain fatty acid (SCFA) analyses showed that the EY2 increased the abundance of beneficial bacteria such as Faecalibacterium, CF231, Coprococcus, Ruminococcus, and Blautia and elevated the concentrations of acetate, propionate, and butyrate. In summary, reducing dietary NE levels to no less than 9.32 MJ/kg improved intestinal health by modulating the gut microbiota and increasing SCFA production.