Centennial Review: Factors affecting the chicken gastrointestinal microbial composition and their association with gut health and productive performance

Abstract

Maintenance of “gut health” is considered a priority in commercial chicken farms, although a precise definition of what constitutes gut health and how to evaluate it is still lacking. In research settings, monitoring of gut microbiota has gained great attention as shifts in microbial community composition have been associated with gut health and productive performance. However, microbial signatures associated with productivity remain elusive because of the high variability of the microbiota of individual birds resulting in multiple and sometimes contradictory profiles associated with poor or high performance. The high costs associated with the testing and the need for the terminal sampling of a large number of birds for the collection of gut contents also make this tool of limited use in commercial settings. This review highlights the existing literature on the chicken digestive system and associated microbiota; factors affecting the gut microbiota and emergence of the major chicken enteric diseases coccidiosis and necrotic enteritis; methods to evaluate gut health and their association with performance; main issues in investigating chicken microbial populations; and the relationship of microbial profiles and production outcomes. Emphasis is given to emerging noninvasive and easy-to-collect sampling methods that could be used to monitor gut health and microbiological changes in commercial flocks.

The effect of Campylobacter jejuni and Campylobacter coli colonization on the gut morphology, functional integrity, and microbiota composition of female turkeys

“…Most investigated gut parameters changed very little over time in control animals, allowing us to interpret temporal changes observed in inoculated animals as effects relating to time post-inoculation rather than age in most cases. However, despite keeping potential influencing factors as constant as possible, changes in environment, season, feed ingredients, and parent flock may have also had an effect on investigated parameters [ 49 , 52 ]. Evidently, this research should also be repeated in other turkey breeds and in male turkeys as results may differ.…”

The Impact of Probiotic Bacillus subtilis on Injurious Behavior in Laying Hens

“…Gut microbiota is the collection of a large community with highly diverse microorganisms that reside within the gastrointestinal tract (GIT) of chickens as well as warm blooded animals. Its function resembles an endocrine organ engaged in multiple pathways (biological systems) including metabolic, immune, endocrine, and neural regulations by integrating the signals received from the internal and external stimulations via the bidirectional communications between the gut and brain [ 6 , 104 , 105 , 106 , 107 , 108 , 109 ]. Maintenance of gut microbial balance is essential for chickens to keep their physiological and behavioral homeostasis, which is critical for optimal growth, reproduction, health, and welfare under the current poultry industry globally.…”

“…Probiotics are commensal bacteria (“direct-fed microbials”, DFM) that offer potential health beneficial effects to the host’s stress response (acute, chronic or both). Several commercial probiotics have been used in poultry production [ 150 , 151 ], and numerous studies have shown that probiotics aid chickens in adapting to their environment and improving their health and welfare by: (1) altering the microbiota profile with beneficial bacteria to prevent the growth of pathogens and to compete with enteric pathogens for the limited availability of nutrient and attachment sites; (2) producing bacteriocins (such as bacteriostatic and bactericidal substances) with antimicrobial function and short chain fatty acids to regulate the activity of intestinal digestive enzymes and energy homeostasis; (3) modulating gut and systemic immunity; (4) restoring the intestinal barrier integrity preventing pathogens from crossing the mucosal epithelium; (5) stimulating the endocrine system and attenuating stress-induced disorders of the HPA and/or sympathetic-adrenal-medullary (SMA) axes via the gut–brain axis; (6) inducing epithelial heat shock proteins to protect cells from oxidative damage; and (7) synthesis and secretion of neurotransmitters such as 5-HT and tryptophan [ 104 , 107 , 113 , 115 , 152 ] ( Figure 3 ).…”

Biomarkers and De Novo Protein Design Can Improve Precise Amino Acid Nutrition in Broilers

“…Moreover, undigested protein and the metabolites from protein fermentation (ammonia, amines, p-cresol and indole [ 14 ]) can negatively affect intestinal health [ 15 ]. Undigested protein in the distal gastrointestinal tract can disrupt gut function and integrity [ 16 ], and can also be used by undesirable pathogenic bacteria [ 17 ]. Furthermore, if amino acids are available in excess or improperly balanced, they need to be catabolized in the liver.…”