# Liquid Microbial-Enzymatic Co-Fermentation of Walnut and Sesame Meals and Its Effects on Nutrient Digestibility in Growing Pigs

## TL;DR

This study shows that fermenting walnut and sesame meals improves their nutritional value and makes them viable protein sources for pig feed.

## Contribution

The study introduces a novel liquid microbial-enzyme co-fermentation method to enhance underutilized plant meals for animal feed.

## Key findings

- Fermentation reduced tannins and crude fiber in walnut and sesame meals.
- Fermented meals improved amino acid digestibility and energy utilization in growing pigs.
- The process positions walnut and sesame meals as alternatives to soybean meal in swine diets.

## Abstract

This research developed a liquid microbial-enzyme co-fermentation process to enhance the nutritional value of walnut meal and sesame meal. The process significantly reduced antinutritional factors such as tannins and crude fiber, while increasing crude protein and acid-soluble protein content. In trials with growing pigs, the fermented products improved the digestibility of key amino acids and enhanced dietary energy utilization. The findings indicate that fermented walnut meal and sesame meal can serve as viable protein alternatives to soybean meal in pig diets, and provide technical support for expanding growing pig feed protein sources and promoting the rational and efficient application of these two meals in growing pig feed.

This study first adopted a liquid microbial-enzymatic co-fermentation process to enhance the nutritional value of walnut meal (WM) and sesame meal (SM), and systematically evaluated its effect on the nutrient digestibility of growing pigs. WM and SM are two underutilized high-protein by-products, whose application is hindered by anti-nutritional tannin and fiber. Optimal fermentation parameters were determined via single-factor experiments and response surface methodology, utilizing a consortium of Lactobacillus I, Candida utilis, and protease. Fermentation significantly reduced tannin (39.41% in WM) and crude fibre (28.79% in WM), reduced tannin (18.67% in SM) and crude fibre (4.00% in SM), while elevating crude protein (10.63% in WM, 7.47% in SM) and acid-soluble protein in both WM and SM. Results of the microstructure of fermented WM and SM revealed structural loosening, surface porosity, and polysaccharide degradation. Microbial community shifts highlighted the dominance of Lactobacillus and Bacillus in fermented substrates. In growing pigs, fermented WM and SM exhibited improved standardized ileal digestibility (SID) of key amino acids (threonine, tryptophan, valine; p < 0.05), alongside enhanced digestible energy (DE) and metabolizable energy (ME) for SM (p < 0.05). These findings demonstrate that liquid co-fermentation effectively degrades anti-nutritional factors, enhances nutrient bio-availability, and positions WM and SM as viable alternatives to conventional protein sources in swine diets, supporting strategies to reduce reliance on soybean meal.