# Effects of Fermented Rice Bran Meal on Growth Performance and Amino Acid Metabolism in Finishing Pigs

## TL;DR

Fermented rice bran meal improves pig digestion and amino acid metabolism compared to unfermented rice bran meal, making it a viable feed alternative.

## Contribution

The study shows that fermenting rice bran meal with Lactobacillus johnsonii L63 and hydrolysis enzymes enhances its nutritional value for pigs.

## Key findings

- Fermented rice bran meal improves intestinal morphology and nutrient digestibility in pigs.
- Unfermented rice bran meal reduces nutrient digestibility and alters liver gene expression related to amino acid metabolism.
- Fermentation increases amino acid transporter gene expression in the jejunum of pigs.

## Abstract

Rice bran meal is a byproduct of extracting oil from rice bran, and it can be used as an alternative feedstock ingredient in animal feeding. Its usage in animal feeding is restricted, especially for monogastric animals, because of its high crude fiber content and antinutritional effects. For its value-adding, solid-state fermentation has been embraced as a beneficial method. This study investigated the possibility of including the fermented product at high levels in pig diets and evaluated whether fermentation lowers antinutritional elements and crude fiber content in rice bran meal. The study also assessed the growth performance, gut microbiota, and amino acid metabolism of pigs eating a diet that includes either fermented or unfermented rice bran meal to ensure they do not endanger human health through the food chain. The findings demonstrated that combining hydrolysis enzymes and Lactobacillus johnsonii L63 with rice bran meal during fermentation increases its nutritional value. While unfermented rice bran meal reduces nutrient digestibility and downregulates liver gene expression linked to amino acid metabolism, fermented rice bran meal enhances intestinal morphology, nutrient digestibility (CP, EE, CF and GE) and tide transporter gene expression in the jejunum.

Due to the lack of corn and soybean meal in animal feeding, rice bran meal (RBM) has been proposed as a beneficial substitute for these feedstocks’ ingredients. Its fermentation by using diverse microbes has been adopted as a beneficial technique. In this study, 18 five-month-old finishing pigs (castrated Duroc × Landrace × Large White) were assigned to three dietary groups with six replicates in each group, designated as the control (CON), unfermented RBM (RBM), and fermented RBM (FRBM) groups. RBM was fermented with a mixture of Lactobacillus johnsonii L63 and hydrolytic enzymes at 37 °C and pH 4.8 for 60 h. The results indicated that incorporating 30% fermented or unfermented rice bran meal into the diets of finishing pigs had no significant effect on growth performance. Regarding serum biochemical parameters, most indicators, including alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and triglycerides, showed no significant alterations. However, in both the unfermented and fermented rice bran meal groups, the concentrations of serum total protein, albumin, globulin, cholesterol, and blood urea nitrogen were significantly decreased (p < 0.05), whereas serum nitric oxide levels were significantly increased (p < 0.05). The FRBM group improved intestinal morphology and the digestibility of nutrients (crude protein, ether extract, crude fiber, and gross energy) by altering the mTORC1 pathway and upregulating the relative expression of amino acid and peptide transporter genes in the jejunum. However, the dry matter digestibility decreased compared to the CON group. The RBM group reduced nutrient digestibility, along with alterations in hepatic gene expression related to amino acid metabolism and transport. Therefore, fermented rice bran meal may offer a potential substitute feed ingredient for use in swine diets when conventional ingredients like corn and soybean meal are in short supply.