# Drying Temperature Dictates Ileal Amino Acid Digestibility of Enzyme-Treated Soybean Meal in 25 kg Pigs

## TL;DR

This study shows that drying enzyme-treated soybean meal at low temperatures improves amino acid digestibility in pigs, making it as nutritious as fishmeal.

## Contribution

The study demonstrates that low-temperature drying preserves the nutritional quality of enzyme-treated soybean meal in pigs.

## Key findings

- Low-temperature-dried enzyme-treated soybean meal had amino acid digestibility comparable to fishmeal.
- High-temperature drying reduced amino acid digestibility in enzyme-treated soybean meal.
- Drying temperature was the critical factor affecting amino acid digestibility, regardless of sugar content.

## Abstract

Soybean meal is a major protein source for pigs, but it contains components that can harm young pigs’ digestion and cause diarrhea. While processing soybean meal with enzymes can improve its quality, a commonly used drying step using high heat might damage the nutrients by causing a chemical reaction (the Maillard reaction) between sugars and proteins. This study tested a new type of enzyme-treated soybean meal from which sugars were removed before processing. The ileal amino acid digestibility of enzyme-treated soybean meal (dried at high or low temperatures) was compared with that of high-quality fishmeal. It was observed that the low-temperature-dried enzyme-treated soybean meal allowed pigs to digest amino acids almost as well as fishmeal, and better than the high-temperature-dried soybean meal. These results demonstrate that drying temperature is a critical factor for enhancing the nutritional value of enzyme-treated soybean meal in pigs.

Soybean meal causes health issues in piglets due to the presence of antigenic proteins. Although enzymatic treatment can break down antigenic proteins, subsequent high-temperature drying may impair amino acid (AA) digestibility via the Maillard reaction. This study evaluated whether the air-drying temperature affects the ileal AA digestibility of a novel reduced-sugar enzyme-treated soybean meal (ESM) in 25 kg pigs, using fishmeal as a high-digestibility reference. In two trials using pigs fitted with simple T-cannulas in the terminal ileum, ileal digestibility was assessed. In trial 1, a replicated 3 × 3 Latin square design with three diets (fishmeal, ESM, and a nitrogen-free diet; two pigs per diet) and three periods were used per square. Fishmeal showed greater apparent (82.50% vs. 45.01%) and standardized (86.60% vs. 48.86%) digestibility of crude protein and all amino acids than ESM dried at 130 °C. In trial 2, eight pigs were allocated to two diets in a two-period crossover design to compare the AA digestibility of ESM dried at high (130 °C; HtESM) and low (80 °C; LtESM) temperatures. LtESM exhibited greater apparent (82.24% vs. 52.40%) and standardized (86.37% vs. 56.47%) digestibility of crude protein and more amino acids than HtESM. Collectively, the drying temperature critically determined the AA digestibility of ESM, irrespective of its reducing sugar content.