Most of the studies selected focus on poultry and three amino acids that are all associated with a significant improvement in host response: methionine, threonine and arginine. one of the most crucial threats to animal production worldwide. Due to the rise of pathogen resistance and consumer concern about chemical-free and environmentally friendly productions, the use of antimicrobials drugs is usually no longer desired. The close relationship Diosmin between nutrition and contamination has led to numerous studies about livestock. Diosmin The impact of feeding strategies, including synthetic amino acid supplementation, on host response to numerous infections has been investigated in different livestock animals. This systematic review provides a synthesis of the experimental studies around the interactions between synthetic amino acid supplementation and immune response to infectious diseases in livestock. Following PRISMA guidelines, quantitative research was conducted using two literature databases, PubMed and Web of Science. The eligibility criteria for the research articles were: (1) the host is usually a livestock animal; (2) the supplementation with at least one synthetic amino acid; (3) at least one mediator of immunity is usually measured; (4) at least one production trait is measured. Data were extracted from 58 selected studies. Articles on poultry were the most numerous; few contained experiments using ruminants and pigs. Most of the authors hypothesized that synthetic amino acid supplementation would particularly improve the animals immune response against intracellular pathogens. An increase in T and natural killer lymphocytes and macrophages activation, intracellular redox state, lymphocytes proliferation and antibodies production were the most explained immune mechanisms associated with synthetic amino acid supplementation. Most of the selected studies focused on three amino acids (methionine, threonine and arginine), all of which are associated with a significant improvement of the host immune response. The use of synthetic amino acid supplementation appears as an encouraging perspective for livestock infectious disease management, and research must concentrate on Mouse Monoclonal to CD133 more analytical studies using these three amino acids. LPS (lipopolysaccharide) injection, notably by the production of several cytokines (IL-1, IL-6 and TNF-) by macrophages . The supplementation with a combination of methionine and cysteine (from 0.8%) was also associated with an increase in the level of anti-IgA in broilers . Few studies have investigated the role of cysteine in the improvement in immune responses. The bibliographic analysis performed here showed only one article in which the impact of cysteine supplementation around the immune response of sheep against and was analyzed. Cysteine was reported to increase blood eosinophil counts and globule leucocytes in the abomasal mucosa following experimental contamination . Further studies need to be conducted in other types of livestock to Diosmin total investigations on metabolic cysteine pathways in response to infectious diseases. Despite the great improvements in our knowledge of sulfur-containing amino acids, there are important areas where further work is required. Cysteine appears to influence certain aspects of immunocompetency in sheep, although the exact role of cysteine in the relationship between wool production and parasite susceptibility requires further elucidation. 4.1.2. Amino Acid Amide The conversation between dietary glutamine and immunity has been well analyzed in mice . Glutamine is usually implicated in purine and pyrimidine biosynthesis in tissues of the immune system , in lymphocyte proliferation  and in cytokine production . In dairy livestock, glutamine is usually considered an excellent feed additive to boost the proteins profile of dairy because of the existence of casein in glutamine residues . Diet supplementation of broiler hens with glutamine (3%), arginine (2%) and threonine (2%) was connected notably with an elevated amount of goblet cells, a lesser.