# The Addition of an Acid Protease Improved the Digestibility of Crude Protein and Amino Acids of Soybean Meal, but Not of Corn, in Piglets

## TL;DR

Adding an acid protease improved amino acid digestion from soybean meal in piglets but had no effect on corn.

## Contribution

The study shows that an acid protease (P2) specifically enhances amino acid digestibility in soybean meal for piglets.

## Key findings

- P2 increased digestibility of lysine, methionine, and other amino acids in soybean meal by 7.5% to 22%.
- Proteases had no effect on corn's protein or amino acid digestibility.
- P1 did not improve soybean meal digestion, but P2 did.

## Abstract

After weaning, young pigs do not produce adequate amounts of enzymes to digest the proteins from vegetable feed ingredients, which are major constituents of their diets. The addition of exogenous protease to pig diets may increase the digestion of dietary protein, improving the utilization of protein and amino acids from the animals’ diets. Thus, the objective of this study was to evaluate two different proteases (P1 and P2) on the digestibility of the protein and amino acids from corn and two sources of soybean meal, with 46% and 48% crude protein, in piglets (13.52 ± 1.96 kg body weight). The two proteases did not influence the digestion of corn protein and amino acids, and P1 did not affect the digestion of protein and amino acids of the two sources of soybean meal. The addition of P2, an acid protease, in soybean meal diets increased the digestion of leucine, lysine, methionine, phenylalanine, alanine, cystine, and glutamate, and their respective digestible values, from 7.5% to 22%, compared to soybean meal without proteases. Thus, P2 was effective in improving the utilization of several amino acids from soybean meal in piglets, enhancing the nutritional value of soybean meal for piglets.

The aim of this study was to evaluate two proteases (P1 and P2) on the apparent and standardized ileal digestibility (AID and SID, respectively), of crude protein (CP) and amino acids (AAs) and apparent total tract digestibility (ATTD) of nutrients and gross energy (GE) of corn and soybean meal, with 46% and 48% CP, in pigs by the index method. Ninety crossbred castrated male piglets (13.52 ± 1.96 kg body weight) were fed a nitrogen-free diet, or diets containing corn or soybean meal as the sole sources of CP and AAs, supplemented or not with 0.05% of P1 or 0.01% of P2, an acid protease. Treatment differences were considered statistically significant at p < 0.05. The inclusion of proteases in corn and of P1 in soybean meal diets did not improve the digestibility of nutrients and energy. Otherwise, the addition of P2, an acid protease, in soybean meal diets increased (p < 0.05) the AID and SID of Lys, Met, Phe, Ala, Cys, and Glu, and the respective digestible AA values, from 7.5% to 22%, compared to soybean meal without proteases. The use of the acid protease can be an important tool to enhance the digestibility of the AAs of soybean meal in piglets.