Dietary phytonutrients and animal health: regulation of immune function during gastrointestinal infections

Abstract

The composition of dietary macronutrients (proteins, carbohydrates, and fibers) and micronutrients (vitamins, phytochemicals) can markedly influence the development of immune responses to enteric infection. This has important implications for livestock production, where a significant challenge exists to ensure healthy and productive animals in an era of increasing drug resistance and concerns about the sector’s environmental footprint. Nutritional intervention may ultimately be a sustainable method to prevent disease and improve efficiency of livestock enterprises, and it is now well established that certain phytonutrients can significantly improve animal performance during challenge with infectious pathogens. However, many questions remain unanswered concerning the complex interplay between diet, immunity, and infection. In this review, we examine the role of phytonutrients in regulating immune and inflammatory responses during enteric bacterial and parasitic infections in livestock, with a specific focus on some increasingly well-studied phytochemical classes—polyphenols (especially proanthocyanidins), essential oil components (cinnamaldehyde, eugenol, and carvacrol), and curcumin. Despite the contrasting chemical structures of these molecules, they appear to induce a number of similar immunological responses. These include promotion of mucosal antibody and antimicrobial peptide production, coupled with a strong suppression of inflammatory cytokines and reactive oxygen species. Although there have been some recent advances in our understanding of the mechanisms underlying their bioactivity, how these phytonutrients modulate immune responses in the intestine remains mostly unknown. We discuss the complex inter-relationships between metabolism of dietary phytonutrients, the gut microbiota, and the mucosal immune system, and propose that an increased understanding of the basic immunological mechanisms involved will allow the rational development of novel dietary additives to promote intestinal health in farmed animals.

Immunostimulatory Potential of Fruits and Their Extracts in Poultry

“…Interestingly, it has been reported that wild birds (Sylvia atricapilla) select their food dependent on the perceived flavonoid content, which when present in the diet were shown to increase the humoral immune response mounted by the birds (55). The presence of such a wealth of compounds, in addition to carbohydrates, proteins, lipids and minerals, make it difficult to establish exact mode of actions of fruits products on immune system (56). Various mechanisms of flavonoids on enzyme function and regulation of gene and protein expression have been reviewed (57).…”

“…The possibility of flavonoids, including quercetin and pomegranate polyphenols, inducing T regulatory cells through the inhibition of mTOR (mechanistic target of rapamycin) has been explored, albeit in human cancer cells (58). If direct mechanisms can be suggested, indirect mechanisms such as those derived from metabolism of phytonutrients and shaping gut microbiota should not be ignored since gut microbiota play important role in immunity against pathogens (12,56). Bioactive contents of fruits pomaces and extracts can be efficient free radical scavengers and iron chelators, which can in turn allow them to prevent diseases and combat pathogens (59).…”

The Benefit of Hedgerow Access on the Health and Growth Rate of Pasture Raised Broiler Chickens

“…We did not observe any changes in the H:L ratio of our chickens (Figure 7), which could indicate that stress was not a factor in the observed changes in immune function, or it could mean that the H:L ratios were affected by other, unmeasured variables (de Jong et al, 2002;Wein et al, 2017). An alternative explanation for the improved immune responses could be ingestion of immunomodulatory agents from the hedge itself; chickens are omnivorous and naturally explorative foragers (Brunberg et al, 2016), and it has been suggested that relatively modest changes in the nutrient composition of the diet can markedly affect the development of immune mechanisms (Williams et al, 2020). While detailing the exact composition of all the flora and fauna available in our hedge was beyond the scope of this study, some potential examples of immune-modulatory agents that may have contributed to this effect include willow leaf (Al-Fataftah and Abdelqader, 2013), phytochemicals, which are natural bioactive compounds that are derived from plants and incorporated into animal feed to enhance productivity (Lillehoj et al, 2018;Williams et al, 2020), polyunsaturated fatty-acids (Liu et al, 2017), and insects (Biasato et al, 2018;Benzertiha et al, 2020;Józefiak et al, 2020).…”

Antiparasitic Effects of Plant Species from the Diet of Great Bustards

“…Flavonoids may reduce the oxidative stress and enhance immunity, so they are selected by different bird species, presumably as a prophylactic drug [44] against pathogens. Polyphenols regulate immune and in ammatory responses during enteric bacterial and parasitic infections in livestock [45], and organic acids can signi cantly reduce microbial contamination in turkeys [46].…”