# Effects of Enzymes or Fermented Feed on Nitrogen Balance, Meat Quality, Intestinal Microbiota Profile and Barrier Functions of Landrace × Rongchang Pigs Fed with a Diversified Low-Protein Diet

## TL;DR

This study shows that adding enzymes or fermented feed to low-protein diets for pigs improves nitrogen use and intestinal health without harming growth or meat quality.

## Contribution

The study introduces practical dietary strategies using enzymes and fermented feed in low-protein diets for sustainable pig farming.

## Key findings

- Dietary supplements reduced nitrogen waste and improved intestinal health in pigs.
- Enzymes and fermented feed enhanced meat quality and fatty acid transport in pigs.
- Fermented feed improved intestinal barrier functions in pigs.

## Abstract

In livestock farming, reducing the reliance on traditional protein feeds, lowering feeding costs, and cutting down on nitrogen-containing waste are key challenges. This study aimed to investigate if adding enzymes or fermented feed to a low-protein diet with diverse ingredients could help solve these issues while maintaining pig growth and meat quality. We tested five diets on pigs, including a normal-protein diet and diversified low-protein diets with or without added enzymes or fermented feed. The results showed that the diversified low-protein diets with enzymes or fermented feed reduced nitrogen waste and enhanced intestinal health without harming growth or meat quality. This research is valuable because it provides a practical way for farmers to feed pigs more sustainably, lowering costs and environmental impact while keeping livestock healthy.

Reducing the dependence on traditional protein sources, and decreasing feeding costs and nitrogen emissions, are important tasks in livestock production. A 5 × 5 Latin square nitrogen balance trial (five castrated male pigs) and an animal growth experiment with 120 Landrace × Rongchang pigs were performed and randomly divided into five diets: a normal crude protein level diet (CON); LP diet; diversified LP containing broken rice, rapeseed meal, and DDGS (DLP); DLP + 0.05% cellulase (DLP + CE); and DLP + 20% fermented feed (FDLP). The CON group showed higher nitrogen intake, urinary nitrogen, and total nitrogen excretion than the other four groups (p < 0.05). The fecal nitrogen was decreased with the LP, DLP + CE, and FDLP groups compared to the CON group (p < 0.05). The mRNA expression of jejunal fatty acid transport protein 1 was upregulated in the LP, DLP + CE, and FDLP groups compared to the CON and DLP groups (p < 0.05). The DLP + CE group showed a higher intramuscular fat content in pigs than the CON and DLP groups (p < 0.05). In the LD muscle, the FDLP and DLP + CE groups upregulated fatty acid synthase expression compared to the LP and DLP groups (p < 0.05). Colonic mRNA expression of zonula occludens-1 and claudin-1 was upregulated in the FDLP group compared to the CON and DLP groups (p < 0.05). These results suggest that the supplementation of cellulase and fermented feed in DLP diets improved nitrogen utilization and intestinal health without compromising growth performance or meat quality in Landrace × Rongchang pigs.