HERBAL GUT MODULATORS IN LIVESTOCK AND POULTRY: ALIGNING PHYTOBIOTICS WITH ANIMAL WELFARE AND AYUSH SYSTEMS

HERBAL GUT MODULATORS IN LIVESTOCK AND POULTRY: ALIGNING PHYTOBIOTICS WITH ANIMAL WELFARE AND AYUSH SYSTEMS

Dr. S. Navaneetha Krishnan M.V.Sc., PGDAW.,

Animal Nutritionist, Dindigul dist, Tamilnadu.

Indroduction:

For over four decades, antibiotics have been used in livestock feed to enhance growth and reduce costs. However, their long-term use at sub-therapeutic levels has contributed to antimicrobial resistance, raising public health concerns. As antibiotic growth promoters (AGPs) are phased out, livestock producers face increased disease risks and economic pressure. This has driven the search for effective, safe alternatives that do not compromise animal performance. Natural options like probiotics, prebiotics, organic acids, and particularly phytogenic feed additives derived from plant extracts such as essential oils, saponins, and bitter compounds—have shown promise. These phytobiotics aid digestion, improve immunity, and exhibit antimicrobial activity, offering a viable solution to maintain poultry health and productivity in antibiotic-free systems.

Phytobotics as gut modulators

The gut plays a vital role in both digestion and immune defense in poultry. Maintaining a balanced gut ecosystem is essential for optimal health and performance. Diet, pathogens, and stress can disrupt this balance, especially in the absence of antibiotic growth promoters (AGPs). With the ban on AGPs, alternatives are needed to sustain gut health and productivity. A healthy gut ensures effective nutrient absorption and protects against pathogens. The intestinal mucosa, comprising epithelial cells, mucus, microbiota, and immune cells, acts as a barrier and plays a key role in gut function. Commensal gut microbiota influence gut development, immune modulation, and digestion. Diet can significantly affect microbial balance. Phytobiotics—plant-derived compounds—have emerged as effective AGP alternatives due to their antimicrobial and immune-boosting properties, helping to maintain gut integrity and improve poultry performance.

Examples of phytobiotic effects on the gut microbiota and immune system of birds.

The mechanisms by which the phytobiotics exert their benefits on the gut remain unclear, but possible mechanisms could be proposed as follows: (1) modulating the cellular membrane of microbes leading to membrane disruption of the pathogens, (2) increasing the hydrophobicity of the microbial species which may influence the surface characteristics of microbial cells and thereby affect the virulence properties of the microbes, (3) stimulating the growth of favourable bacteria such as lactobacilli and bifidobacteria in the gut, (4) acting as an immunostimulatory substance and (5) protecting the intestinal tissue from microbial attack . The phytobiotics especially those from the group of essential oils have been reported to improve flavour and palatability of feed and may thus improve the feed intake and performance .

Probable Mode  of  Action

It has been reported that herbs, spices and their extracts can stimulate appetite and endogenous secretions such as enzymes or have antimicrobial, antiviral, coccidiostatic or anthelmintic, antiinflamatory activities in monogastric animals. Oligosaccharides and polysaccharides such as inulin (fructan), fructo oligosaccharides (FOS) and arabinogalactans, which are extracted from plants, and sulfated fucans, which are extracted from seaweeds, are potential substitutes for currently used antibiotic growth promoting compounds .      The mode of action of most phytobiotics is still not fully understood. However, the following are some of the potential mechanisms by which they exert their beneficial effects and improve performance.

Direct Antibacteria, Anticoccidial and Antiviral Effects

Plant-derived substances, especially essential oils, have long been recognized for their antimicrobial effects. Compounds like thymol, carvacrol (oregano), and eugenol (clove) inhibit pathogens such as Salmonella, E. coli, and Clostridium perfringens. Cinnamon oil enhances nutrient digestibility, while turmeric and mushroom extracts reduce microbial loads and support gut health. These phytobiotics not only kill harmful microbes but also reduce toxic by-products like volatile fatty acids and biogenic amines, promoting better digestion and nutrient use. Tannins in chestnut and quebracho extracts show antiviral effects by preventing virus-cell attachment and inhibiting viral enzymes. Their mechanism includes disrupting microbial membranes and altering surface hydrophobicity, which affects pathogen virulence. Tannic acid may also starve microbes by binding essential iron. These effects, especially potent against Gram-positive bacteria, are particularly valuable in young animals with immature gut flora, making phytobiotics promising natural alternatives to antibiotic growth promoters.

Prebiotic Effects

Prebiotics are non-digestible oligo- and polysaccharides that lower gut pH, inhibiting pathogens, boosting immunity, and supporting beneficial microbes like Lactobacillus and Bifidobacterium. These compounds, found in plants and mushrooms, help create a balanced gut flora, reducing diseases such as necrotic enteritis and coccidiosis. Supplementation with extracts like thyme, yarrow, capsaicin, and cinnamaldehyde lowers harmful bacteria such as C. perfringens and E. coli. Prebiotics promote the production of short-chain volatile fatty acids (SCFAs), which suppress pathogenic bacteria and support colon cell health. Butyrate, a key SCFA, nourishes intestinal cells and boosts gut barrier integrity. Studies show that inulin, oligofructose, and soybean-derived polysaccharides enhance SCFA production and microbial balance, while reducing gut pH. This acidic environment supports mucus production and encourages dominance of beneficial bacteria over harmful strains, making prebiotics vital for gut health in poultry and livestock.

Phytobiotic compound or phytobiotic effects

Effects of plant–derived bioactive compounds on gut–associated microflora

 Competitive blocking of bacterial adhesion

Lectin–carbohydrate receptor interactions are the main mechanism in adhesion of pathogens to the brush border of the gut mucosal epithelium. Many prebiotic and phytogenic bioactive substances can have a direct effect on certain pathogenic bacteria either by specific adhesion of pathogens through the ‘lectin–receptor’ mechanism (agglutination) by blocking the adhesion of pathogens onto the mucosal layer of the intestine. One such group of bioactive compound that has been studied extensively is the phosphorylated mannanoligosaccharides (MOS) from yeast cell walls. Dietary MOS have been shown to decrease the prevalence of strains of salmonella expressing type–1 fimbriae in young chicks under laboratory conditions .Recently, compounds such as oligomannans and lectins could bind to the enterocyte receptors that are present on the cell walls of pathogenic bacteria, thus preventing them from colonizing the gut. Certain prebiotic compounds such as pectin, guar gum and oat gum, which have a protective function in the mucosal layer the intestine, act by preventing the colonization of pathogenic bacteria.

Immunostimulatory effects

Certain plant polysaccharides act as immunostimulants by enhancing gut-associated lymphoid tissue (GALT) responses, which are vital for immunity in farm animals. Compounds from mushrooms like Lentinus edodes and Tremella fuciformis, and herbs like Astragalus membranaceus, activate both innate and adaptive immunity in chickens. Saponins from Quillaja saponaria serve as effective mucosal adjuvants, while low-molecular-weight polysaccharides like achyranthan have shown greater immune-boosting potential than larger ones. Prebiotics such as inulin and oligofructose enhance the production of interleukin-10 and secretory IgA, and upregulate macrophage-dependent immune responses. For these effects, oligosaccharides must act before or escape fermentation in monogastric animals. Additionally, sulphated polysaccharides from seaweeds (especially brown and red varieties) are known to regulate cytokine production and activate macrophages, though their direct effects on livestock performance need further research. Overall, plant-based polysaccharides show strong promise as natural immune enhancers in animal nutrition.

Stimulation of digestive enzymes

Another possible mode of action of phytogenic bioactive compounds on growth performance of farm animals could be their effects on the activities of digestive enzymes. Dietary supplementation of fructooligosaccharides improved daily body weight gain of male broiler chickens by increasing the activities of amylase and protease. Furthermore, a study with broiler chickens indicated that feeding a diet containing a commercial blend of essential oils (CRINA) in combination with lactic acid induced a significant increase in activities of digestive enzymes of the pancreas and intestinalmucosa of birds, leading to a significant increase in growth. A product from the rhizomes of Sanguinaria canadensis is frequently used in Europe for poultry while garlic and horseradish, when included in feed, stimulate the production of saliva and gastric juices. In context with highly productive agricultural livestock it has to be mentioned that stimulation of digestive secretion is not a beneficial action per se. It is often a concomitant phenomenon of an irritating action being accompanied by shortening of intestinal villi length (resulting from higher tissue turnover) and a higher passage rate of digesta. Nevertheless, such effects may have a beneficial action at low hygiene as they counteract the attack of potential pathogens to the intestinal tissue.

Feed Intake and Antioxidant Action of Phytobiotics

Phytobiotics, particularly those containing essential oils, can enhance feed intake in poultry by improving flavor and aroma, making the diet more palatable. Their antioxidant properties may help preserve the feed’s sensory quality, especially in fat-rich diets. While the exact mechanism remains unclear, some studies suggest increased saliva production or digestive stimulation may play a role. Interestingly, low levels of tannins—once considered anti-nutritional—have shown benefits when combined with probiotics, improving gut health and feed palatability

Additionally, many phytobiotics possess strong antioxidant properties due to phenolic terpenes. Substances like rosemary and olive leaf extracts reduce lipid oxidation, thereby improving the shelf life and nutritional value of meat products, especially those rich in polyunsaturated fats. These natural antioxidants not only benefit product quality but also support animal health. Some phytobiotics also have pharmacological effects, such as easing digestion and enhancing glucose absorption, further contributing to improved performance and feed utilization.

Pharmacological actions:-

Another field of phytobiotic actions comprises astringent and denaturizing properties. Tannins are well known examples, proven and tested by folk medicine and regular veterinary use for treatment e.g. of diarrhoea. When applied to healthy animals as feed additives on a long term basis, however, the astringent and denaturizing property of tannins may reduce intestinal villi length and impair function of other protein based feed additives (e.g. phytase, NSP degrading enzymes). This ambivalence in efficacy for veterinary vs. Feed additive purposes may restrict the broad use of such phytobiotics in agricultural livestock including poultry.

 Conclusion
Phytobiotics have shown promise in improving gut health and performance in monogastric livestock, mainly through their antimicrobial effects. However, their efficacy can vary due to differences in plant source, processing, and animal conditions. While they help stabilize gut function, they are not cures for specific diseases or poor environments. Research on their safety, mechanisms, and optimal use is still evolving. Larger, controlled studies are needed to confirm their benefits and guide consistent application in commercial poultry production. Phytobiotics hold potential, but practical use requires further investigation and standardization.

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