ORIGINAL RESEARCH article
Front. Anim. Sci.
Sec. Animal Nutrition
This article is part of the Research TopicNew Horizons in Gut Microbiome Research for Enhancing Livestock ProductivityView all 40 articles
Optimizing Gut Microbial Balance and Growth Performance in Growing Pigs Through Protease-Supplemented Low Protein Diets
Provisionally accepted
Sungbo Cho1,2
Robie Vasquez2
Vetriselvi Sampath1,2
Ji Hoon Song2Jae Seung Lee2
Demin Cai3,4
Dae-Kyung Kang1,2*
In Ho Kim1,2*- 1Smart Animal Bio Institute, Dankook University, Cheonan, Republic of Korea
- 2Department of Animal Biotechnology, Dankook University, Cheonan, Republic of Korea
- 3Jiangsu Key Laboratory of Animal Genetic Breeding and Molecular Design, College of Animal Science and Technology, Yangzhou University, Yangzhou, China
- 4International Joint Research Laboratory in Universities of Jiangsu Province of China for Domestic Animal Germplasm Resources and Genetic Improvement, Yangzhou, China
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Environmentally friendly pork production is crucial to the pig industry, where the enhancement of growth performance and feed efficiency with reduced environmental impacts is favored. This study aimed to evaluate the effect that protease supplementation in a low crude protein diet has on the growth performance, nutrient digestibility, nitrogen retention, and gut microbiome in growing pigs. Eighty pigs (Landrace × Yorkshire × Duroc; 24.72 kg) were selected, and based on initial body weight and sex, randomly allocated to one of the following dietary treatments: H, 16% crude protein (CP) diet; L, 14% CP diet; L+E1, low CP diet + 0.1% protease; and L+E2, low CP diet + 0.2% protease. Each treatment comprised four replicates with five pigs per pen. Pigs fed a low CP diet with protease supplementation showed a significantly higher body weight, average daily gain, and feed conversion ratio than those fed a high CP diet. In addition, ammonia emissions were lower in the L+E2 group than in the L group. Based on microbiome analysis, the L+E1 and L+E2 groups showed an increased Firmicutes-to-Bacteroidota ratio and elevated expression of pathways related to carbohydrate metabolism, coinciding with higher concentrations of short-chain fatty acids, such as butyrate and propionate, which support intestinal health. Additionally, the predicted function of the microbiota of pigs fed protease exhibited reduced nitrogen and sulfur metabolism, suggesting a potential reduction in excreted odorous compounds. These findings highlight the role of protease in enhancing growth performance and feed efficiency by modulating gut microbial This is a provisional file, not the final typeset article composition and metabolic functions and reducing noxious gas emissions. Also, potential feed-cost savings are inferred from lower CP formulation.
Keywords: Crude protein, Growing pigs, growth performance, gut microbiome, N retention, Protease
Received: 06 Oct 2025; Accepted: 11 Feb 2026.
Copyright: © 2026 Cho, Vasquez, Sampath, Song, Lee, Cai, Kang and Kim. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence:
Dae-Kyung Kang
In Ho Kim
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