Threonine, arginine, and glutamine: Influences on intestinal physiology, immunology, and microbiology in broilers

Abstract

Even though the intestine represents a small proportion of body weight in broiler chickens, its requirements for energy and nutrients are high. A healthy broiler intestine has a well-coordinated immune system that must accommodate commensal microbiota while inhibiting the colonization and proliferation of harmful pathogens. Modern commercial intensive practices impose a high sanitary pressure that may exacerbate the progression of intestinal diseases such as coccidiosis and necrotic enteritis. The incidence of these diseases may increase worldwide due to mounting pressure to limit the use of subtherapeutic antibiotics as growth promoters or ionophores for coccidial suppression/prevention in the diets of broilers. For this reason, altering dietary concentrations of some amino acids, particularly trophic amino acids, may be beneficial to modulate the intestinal physiology, immunology, and microbiology of broilers. Trophic amino acids, such as threonine, arginine, and glutamine, play a very important role on the intestinal mucosa and may support increased epithelial turnover rates to improve intestinal recovery following an insult. Furthermore, these amino acids may help to minimize over-activation of the innate immune system, which is the most expensive in terms of nutrients and energy, as well as modulate the intestinal microbiota. The objective of this review is to provide insight into the potential role of trophic amino acids in these processes and report some updated studies of their use in diets for broiler chickens.

Expression of selected genes encoding mechanistic pathways, nutrient and amino acid transporters in jejunum and ileum of broiler chickens fed a reduced protein diet supplemented with arginine, glutamine and glycine under stress stimulated by dexamethasone

“…Similar to a previous study (Barekatain, Nattrass, et al, 2019), DEX downregulated MUC‐2 gene expression in jejunum of injected birds. Among amino acids, Thr, Arg and Gln have been shown to play a role in mucin production in poultry (Bortoluzzi, Rochell, & Applegate, 2018). Additionally, Gly can indirectly alter mucin turnover, either by avoiding the catabolism of Thr into Gly or serving as a substrate for synthesis of mucin, given the central domain of mucin is high in Gly (Ospina‐Rojas, Murakami, Oliveira, & Guerra, 2013).…”

Nutritional significance of amino acids, vitamins and minerals as nutraceuticals in poultry production and health – a comprehensive review

“…Amino acids are functional and structural units of protein, nutritionally classified into two groups: non-essential (synthesized in the body) and essential amino acids (cannot be synthesized rapidly enough to meet the metabolic requirement). Amino acids play vital physiological roles in the body (Bortoluzzi et al 2018;Debnath et al 2019). After absorption, amino acids are assembled and metabolized to form proteins that are used to build different body tissues.…”

Application of omics technologies for a deeper insight into quali-quantitative production traits in broiler chickens: A review

“…It has also been reported that threonine as well as methionine plus cysteine in-ovo administration can modulate the expression of immune genes in liver and intestine of broiler chickens [ 147 ]. Recently, the effects of dietary threonine, arginine and glutamine on intestinal mucosa health and integrity, as well as on the innate immune system activation, have been extensively reviewed by Bortoluzzi et al [ 148 ].…”