Functional Amino Acids in Pigs and Chickens: Implication for Gut Health

Abstract

In pigs and broiler chickens, the gastrointestinal tract or gut is subjected to many challenges which alter performance, animal health, welfare and livability. Preventive strategies are needed to mitigate the impacts of these challenges on gut health while reducing the need to use antimicrobials. In the first part of the review, we propose a common definition of gut health for pig and chickens relying on four pillars, which correspond to the main functions of the digestive tract: (i) epithelial barrier and digestion, (ii) immune fitness, (iii) microbiota balance and (iv) oxidative stress homeostasis. For each pillar, we describe the most commonly associated indicators. In the second part of the review, we present the potential of functional amino acid supplementation to preserve and improve gut health in piglets and chickens. We highlight that amino acid supplementation strategies, based on their roles as precursors of energy and functional molecules, as signaling molecules and as microbiota modulators can positively contribute to gut health by supporting or restoring its four intertwined pillars. Additional work is still needed in order to determine the effective dose of supplementation and mode of administration that ensure the full benefits of amino acids. For this purpose, synergy between amino acids, effects of amino acid-derived metabolites and differences in the metabolic fate between free and protein-bound amino acids are research topics that need to be furtherly investigated.

Intestinal Barrier Function and Performance of Broiler Chickens Fed Additional Arginine, Combination of Arginine and Glutamine or an Amino Acid-Based Solution

“…Broilers fed corn-based diets are more conducive to Gln supplementation due to lower concentration of Gln in corn relative to wheat particularly when reduced protein diets are used [25]. The positive growth performance by feeding a combination of Gln and Arg may also be explained by their stimulatory effects on gut development (e.g., provision of energy source for enterocytes, synthesis of polyamines), immune response and function, as well as epithelial cells regeneration [2,26].…”

“…Amino acids play fundamental roles in the optimum functionality of the intestine with increasing evidence of regulation of intestinal barrier function by concentration of amino acids in the diets [1]. There is evidence for the role of amino acids such as glutamine (Gln), arginine (Arg), and threonine (Thr) having positive effects on controlling Animals 2021, 11, 2416 2 of 17 permeability, promoting cell proliferation, and stimulating several metabolic pathways such as mTOR [1,2].…”

“…a,b Means sharing a different superscript differ significantly at the p level shown 1. MIX contained Arg, Gln, Thr, and grape extract 2. Pooled standard error of the mean (n = 48).…”

“…a-c Means within the same column with different superscript differ significantly for the p level shown for main effects and p < 0.05 for treatment effect when there is a significant DEX × Diet interaction. 1 MIX contained Arg, Gln, Thr, and grape extract 2. Pooled standard error of the mean (n = 48).…”

Effects of Dietary Supplementation with Red Yeast (Sporidiobolus pararoseus) on Productive Performance, Egg Quality, and Duodenal Cell Proliferation of Laying Hens

“…This implies that the red yeast supplementation in laying hen diet benefited the gut health as indicated by increased duodenal histology and cell proliferations. On a cellular level, increased PCNA (protein which increases DNA polymerase activity) and mitotic index are described as indicators of cell proliferation [57]. Investigations in broilers receiving resistant starch (prebiotic property) have observed that duodenal mitotic index (the numerical percentage of PCNA-positive nuclei) was greater in chickens receiving a diet with 12% corn resistant starch than chickens receiving control diet [58].…”