Introduction

Gut: The First Line of Immune Defence
The intestinal defence system consists of several interconnected components, including the mucus layer, intestinal epithelial cells, tight junctions, antimicrobial substances, gut microbiota and gut-associated lymphoid tissue (GALT).

The epithelial cells form a physical barrier between the intestinal contents and the internal tissues. Tight-junction proteins such as occludin, claudins and ZO-1 regulate the movement of substances between epithelial cells. The mucus layer provides an additional protective environment, while immune cells located within and beneath the intestinal mucosa continuously monitor microbial and dietary antigens.
Thus, the intestine acts as both a selective absorption system and an immune surveillance system.

Gut Microbiota and Immune Development
The intestinal tract contains a complex microbial ecosystem. A balanced microbial population can contribute to pathogen exclusion, production of microbial metabolites, maintenance of intestinal integrity and modulation of host immune responses.
Beneficial microorganisms and their metabolites communicate with intestinal epithelial cells and immune cells. Among these metabolites, short-chain fatty acids (SCFAs) such as acetate, propionate and butyrate are particularly important because they can influence epithelial health, immune-cell activity and inflammatory responses. Therefore, gut microbiota and immunity have a bidirectional relationship. A healthy microbiota supports a healthy intestinal barrier and balanced immune signalling. At the same time, the immune system regulates microbial populations and helps maintain intestinal homeostasis.
What Happens When Gut Health Is Compromised?
Commercial poultry are exposed to several factors capable of disturbing gut integrity, including coccidiosis, bacterial pathogens, mycotoxins, heat stress, poor water quality, nutritional imbalance and dysbiosis.

A compromised gut can result in epithelial damage, disruption of tight junctions, increased intestinal permeability, inflammation and oxidative stress, altered immune response and reduced performance. This process is sometimes described as increased “intestinal permeability” or “leaky gut.”

When intestinal integrity is compromised, nutrients may not be utilized efficiently and microbial products can interact more extensively with host immune mechanisms. The bird may consequently spend additional nutrients and metabolic resources on inflammation and tissue repair rather than growth or egg production.

Coccidiosis, Mycotoxins and Heat Stress

Coccidiosis is a classic example of the gut–immune relationship. Eimeria infection damages intestinal epithelial cells, alters intestinal morphology and stimulates an inflammatory and immune response. Consequently, coccidiosis control is not only a parasite-management issue but also a gut health, nutrition and immune-management issue.

Similarly, mycotoxins can affect intestinal integrity, oxidative status, microbial balance and immune function. Their impact may therefore extend beyond the feed itself to the overall gut–immune axis.

Heat stress is particularly important in tropical poultry production. Heat stress can alter feed intake, intestinal physiology, microbial balance and barrier integrity, potentially increasing inflammatory and oxidative stress. Maintaining gut integrity during heat stress is therefore an important component of maintaining flock resilience.

Gut Health and Vaccine Response
An effective vaccination program depends on the bird’s ability to recognize antigens and develop appropriate humoral and cellular immune responses. This requires adequate availability of energy, amino acids, vitamins, minerals and antioxidants. Therefore, gut health indirectly supports the nutritional foundation required for immune responses. A healthy intestine facilitates nutrient digestion and absorption, while intestinal inflammation or damage can increase nutrient requirements for tissue repair and immune activity. It is important, however, to recognize that good gut health alone does not guarantee vaccine success. Vaccine quality, administration, maternal immunity, biosecurity, disease pressure, nutrition and environmental conditions also influence the final immune response.

Nutritional Support for the Gut–Immune Axis
Nutrition is one of the most important tools for supporting the gut–immune relationship. Zinc contributes to epithelial integrity, cellular proliferation, enzyme activity and immune-cell function. Selenium is an important component of antioxidant defence systems and supports cellular protection and immune function. Vitamins A and E also contribute to mucosal integrity, antioxidant protection and immune responses.
Nutritional interventions such as probiotics, prebiotics, postbiotics, organic acids, enzymes, yeast-derived products, MOS and β-glucans may be used as part of integrated gut-health programs. MOS can support gut health through microbial interactions and pathogen-exclusion mechanisms, while β-glucans can interact with innate immune pathways and influence immune-cell activity. However, responses depend on product source, structure, dose, bird age, diet and challenge conditions; therefore, these products should be evaluated based on scientific evidence and field performance rather than assuming that all products have identical effects.

Practical Approach for Commercial Poultry
A successful gut-health program should not depend on a single feed additive. It should combine:
– High-quality and properly stored feed
– Regular mycotoxin monitoring and management
– Good drinking-water quality and sanitation
– Effective coccidiosis control
– Appropriate vaccination and biosecurity
– Heat-stress management
– Balanced amino acid, vitamin and mineral nutrition
– Appropriate use of probiotics, prebiotics/postbiotics and other gut-health products
– Monitoring of litter quality, feed intake, FCR, mortality and flock uniformity

Conclusion
The gut and immune system should be viewed as two interconnected components of the same biological defence network. A healthy intestinal microbiota, intact epithelial barrier and properly functioning GALT provide the foundation for balanced immune development and response. For commercial poultry, the concept is simple: “Protect the gut to support immunity, and support immunity to maintain flock resilience.”
Gut health is therefore not only about digestion and FCR. It is closely connected with nutrient utilization, immune development, disease resistance, vaccine responsiveness and ultimately flock productivity.
The future of poultry nutrition will increasingly focus on managing the gut–microbiota–immune axis through integrated nutrition, health and farm-management strategies rather than addressing individual problems in isolation.

Lode Nollet, Global Product Manager Poultry Enzymes, Huvepharma

Nutritional strategies to support the production of high quality, low cost and safe animal products are a must nowadays. The relationships between health, nutrition, welfare, and environment need to be considered. In poultry production, increasing feed costs are imposing pressure on the profitability of the farmer, so nutritionists seek to reduce feed costs whilst maintaining animal performance and gut health. Several strategies, with tangible tools to support this, are discussed in this article.

CONTROLLING COCCIDIOSIS

Coccidiosis, caused by protozoan parasites of the genus Eimeria, is one of the most widespread and difficult to manage poultry diseases, resulting in considerable economic losses in the broiler industry. Insufficient or inadequate control of coccidiosis will result in gut health damage and provide a pathway for other pathogens to proliferate.

For instance, suboptimal coccidiosis control combined with a high amount of undigested protein will create an ideal situation for the proliferation of Clostridia spp. Birds suffering from clinical coccidiosis will show typical signs like diarrhoea, bloody droppings, increased mortality, decreased feed intake and impaired performance.

Inadequate control of coccidiosis leads to impaired growth and feed conversion ratio, without the presence of evident clinical signs. This is subclinical coccidiosis.

Intensive methods of production of poultry favour the reproduction of Eimeria. Consequently, coccidiosis is a continuing problem requiring constant attention and, in the case of broilers, a need for continuous supplementation with anticoccidial drugs or coccidiosis vaccines, in addition to in-feed anticoccidials. Coccidiosis control combined with a good monitoring programme will be the base of any gut health management programme.

IMPROVING FEED DIGESTIBILITY

Improving digestibility of the feed can be achieved by selecting highly digestible feedstuffs. However, this will increase the feed price. The improvement of the digestibility of feed by using enzymes able to degrade Non-Starch Polysaccharides (the so-called NSPases) will not only lead to lowering the feed cost at formulation, but also exert a positive effect on the bird’s gut health.

The NSPases contain xylanase or xylanase-based enzymatic complexes, and their mode of action includes the hydrolysis of soluble arabinoxylans, which minimises intestinal viscosity, preventing the overgrowth of microflora and thereby reduces gut health disorders.

Together with the efficient reduction in viscosity, NSPases will also hydrolyse insoluble arabinoxylans. This action will unlock nutrients (mainly starch and proteins) which are trapped in the cell walls of the vegetable feed ingredients (the so called ‘cage effect’ of insoluble fibres).

Using the correct NSPase leads to improved digestibility of starch and protein. The latter is of particular importance as high levels of undigested protein in the (last) part of the intestine is a breeding ground for protein-loving pathogens like Clostridium spp, causing necrotic enteritis.

The breakdown of arabinoxylans by NSPase also yields arabino- oligosaccharides (AXOS) which are known to be fermented by the microflora in the lower part of the intestine to butyrate, which is a major energy source for villi regeneration allowing good gut health status.

Phytases have been shown not only to break down phytate to release phosphorus, but by doing so, to also destroy the anti-nutritional factor phytate.

This not only leads to a reduction of endogenous protein losses, but also liberates protein and amino acids which are complexed by phytate, enhancing their digestibility.

SUPPORTING THE MICROBIOTA

The relationship between a healthy gut and the animal’s microbiota is undeniable. As part of the holistic approach, the inclusion of probiotics in the nutritional programme offers a way of supporting gut health from a microbial perspective.

The mode of action of probiotics is usually multifactorial, including (but not limited to) the production of beneficial metabolites or the direct competition with unwanted bacteria. As a result, probiotics often help to balance the present microbiota and improve its robustness, supporting general gut health in the process. Probiotics can be incorporated into the feed or drinking water, depending on the strain and formulation used.

Although there are many commercial options available, the preferred product of choice should be based on a single unique strain, capable of forming spores and with a proven and researched mode of action. Such probiotics increase the ease of use, whilst ensuring product efficacy.

Good examples are B-Act®, containing viable spores of Bacillus licheniformis, based on Clostridium butyricum. Probiotics allow producers to support their animals’ gut health efficiently, setting them up for a successful production period from start to finish.

CONCLUSION

Gut health management is of paramount importance to the profitability of poultry farming. The strategy behind managing optimal gut health should contain a combination of the most important control tools on the market available today: an adequate and well thought-through coccidiosis control programme, combined with an NSP enzyme and a phytase, and topped off by a well-functioning probiotic.

To know more, please contact Huvepharma technical team

Huvepharma SEA (Pune) Pvt. Ltd.

42, ‘ Haridwar’, Road 2 A/B, Kalyani Nagar, Pune 411006 Customer Care Contact: +91 20 2665 4193

Email: salesindia@huvepharma.com Website: www.huvepharma.com