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Dietary Supplementation of Methionine, Tryptophan, and Threonine for Pigs Under Sanitary Challenges: Current Knowledge and Future Directions
by
, , , , , , and
Graziela da Cunha Valini
1
,
Alícia Zem Fraga
2,
Ismael França
1,
Danilo Alves Marçal
3,
Pedro Righetti Arnaut
1,
Alini Mari Veira
1
,
Marllon José Karpeggiane de Oliveira
1,
Ines Andretta
4
and
Luciano Hauschild
1,* 1
Department of Animal Science, School of Agricultural and Veterinarian Sciences, São Paulo State University (Unesp), Jaboticabal 14884-900, Brazil
2
Department of Animal Science, Universidade Federal Rural do Rio de Janeiro, Seropedica 23890-000, Brazil
3
Graduate Program in Animal Production, Universidade Brasil, Fernandopolis 15600-000, Brazil
4
Department of Animal Science, Faculty of Agricultural and Life Sciences, Universidade Federal do Rio Grande do Sul, Porto Alegre 91540-000, Brazil
*
Author to whom correspondence should be addressed.
Vet. Sci. 2025, 12(9), 794; https://doi.org/10.3390/vetsci12090794 (registering DOI)
Submission received: 2 July 2025
/
Revised: 12 August 2025
/
Accepted: 20 August 2025
/
Published: 23 August 2025
(This article belongs to the Section Veterinary Microbiology, Parasitology and Immunology)
Simple Summary
Pigs raised in commercial production systems are often exposed to unsanitary conditions that impair health, welfare, and growth performance. An increase in environmental pathogenic pressure can be exacerbated when biosecurity protocols, stocking density, and the degree of hygiene of the facilities are not adequately followed. These sanitary challenges trigger immune and metabolic responses that divert nutrients (in particular, amino acids; AA) from growth to defense mechanisms. Methionine, tryptophan, and threonine are considered functional AA due to their roles in supporting immune function, antioxidant defense, and gut integrity. This review emphasizes the critical role of these AA in alleviating the detrimental effects of sanitary stress. Furthermore, the integration of functional AA supplementation with precision feeding may offer promising solutions to enhance pig resilience and sustainability in antibiotic-free production systems.
Abstract
Sanitary challenges (SCs) may alter the health status, growth performance, and pigs’ welfare. Changes in amino acid (AA) plasma concentrations have been observed in inflammatory-challenged pigs which may be associated with key factors, such as: (1) the synthesis of immune components to support innate and/or adaptive immune responses, (2) the redistribution of nutrients from growth and production functions toward cells and tissues involved in inflammatory and immune responses, and (3) decreased anabolism and/or increased catabolism of skeletal muscle to increase the availability of nutrients, often as a consequence of reduced feed intake. Due to their health-promoting effects, nutritional strategies involving AA may help mitigate the negative impacts of SC. Methionine, tryptophan, and threonine, beyond serving as protein building blocks, are considered functional AA because they support immune system function, enhance intestinal barrier integrity, modulate inflammatory responses, and limit oxidative stress. Additionally, the review highlights the influence of individual variability, such as differences in body weight, on nutritional requirements and responses to AA supplementation for pigs under SC. The integration of nutritional strategies tailored to immune-challenged pigs offers promising avenues to improve productivity and animal welfare in commercial swine production systems with increasing restrictions on antibiotic use.
Keywords:
health; immune system; inflammation; nutrition; swine
