Restoring healthy gut microbiome in poultry using alternative feed additives with particular attention to phytogenic substances: Challenges and prospects

Abstract

The majority of pathologies in poultry are linked to intestinal chronic inflammation due to a disbalance of the gut microbiota. Thus, a healthy microbiota drives the gut integrity, and the gut’s biological and metabolic functionalities, including efficacious use of nutrition, but also immunity, and neuroendocrine systems. However, many external factors are disturbing a stable, healthy gut microbiota. Heat stress, dysbiosis, leaky gut syndrome, and mycotoxins are the main “secret killers” in poultry that lead to chronic oxidative stress and inflammation, which in turn impact the health and animal performance. Additionally, chronic stress in poultry is linked with the emergence of antimicrobial resistance (AMR), which the WHO has recently identified to be among the most important problems threatening human health globally that increased the demand for safe antimicrobials to treat the collateral damages resulting from dysbiosis. Several alternative feed additives such as probiotics, prebiotics, fatty acids, and amino acids have been described to restore intestinal microbiota. Additionally, some phytogenic substances have anti-inflammatory and antioxidant activities. These natural products are also capable to modulate gut microbiota in a symbiotic equilibrium, thereby enabling the intestinal tract to withstand both infectious and non-infectious stressors. Nevertheless, several challenges, such as the bioavailability, rate of absorption, quality inconsistency, public acceptance, and cost-effective delivery methods, make the feasibility and application of phytogenic substances on a commercial scale complicated. In this review, the main drivers of chronic inflammation in poultry have been discussed. Additionally, the potential use of alternatives to antibiotics to restore the gastrointestinal microbiota in poultry and the possibilities for overcoming breakdowns in poultry farming were highlighted

The effects of essential oil from Lippia origanoides and herbal betaine on performance, intestinal integrity, bone mineralization and meat quality in broiler chickens subjected to cyclic heat stress

“…Free radicals destroy cells and tissues, causing inflammation and disease. Antioxidants help to neutralize free radicals and protect cells from damage ( Shehata et al, 2022b ). Similarly, betaine supplementation has been shown to increase villi height in the duodenum of chickens by increasing the secretion of mucus and improving the integrity of the intestinal mucosal barrier in chickens under long-term heat stress ( Liu et al, 2019 ).…”

“…Several investigators have studied the effects of EO on chickens under heat stress conditions ( Shehata et al, 2022b ; Yilmaz and Gul, 2023a ; Mangan and Siwek, 2023 ). These studies have shown that EO can improve performance, while reducing the negative outcomes of heat stress, such as reduced water intake, oxidative stress, and inflammation ( Chowdhury et al, 2023 ; Das et al, 2023 ; Rafeeq et al, 2023 ).…”

Anti-Inflammatory and Antioxidative Phytogenic Substances against Secret Killers in Poultry: Current Status and Prospects

“…Phytogenic compounds have been evaluated as potential alternatives to antimicrobials in poultry [ 88 ]. However, the bioavailability, rate of absorption, and cost-effective delivery methods for phytogenic compounds make their feasibility and application on a commercial scale complicated [ 236 ]. The efficacy of phytogenic compounds has not been regulated since most of these compounds are generally accepted as safe by the US Food and Drug Administration.…”

“…Although the biochemical structure of polyphenols results in their high biological activity as antioxidants in vitro, their biological efficiency in animals is hindered, due to the poor oral bioavailability of the polyphenols, which is explained by the contradictory findings from both in vivo and in vitro experiments [ 239 , 240 ]. The lower efficiency of polyphenols in vivo could be attributed to the following several factors [ 236 ]: (i) the low uptake and assimilation of polyphenolic substances may lead to insufficient minimal concentrations in target tissues, meaning they are not effective as scavengers of free radicals; (ii) the extensive biotransformation that occurs in the liver and intestinal tract may influence the functional forms of these substances, which in turn adversely impacts biological activities, including the antioxidant properties [ 142 ], and/or (iii) they may be metabolized and quickly eliminated from the bloodstream [ 241 ]. For these reasons, the observed in vivo antioxidant effects could be indirect effects that occur through the upregulation of antioxidant defenses by the substantial protective effect in the gastrointestinal tract and their effects on Nrf2 and NF-κB [ 140 ].…”

“…Lactic acid bacteria derived from chicken cecal contents have been shown to increase the bioavailability of flavonoids by increasing flavonoid hydrolysis, but this was affected by the carbon source available for microbial fermentation [ 247 ]. Optimizing the method of encapsulation and understanding the impacts of microbial fermentation on the rate of degradation and kinetics of phytogenic compounds are also required [ 236 ].…”