Nutrition-driven gut health

Nutrition-driven gut health is emerging as a practical approach to support animal well-being while reducing antibiotic reliance. By targeting the gut microbiome, enhancing nutrient absorption, and modulating immune function, these strategies can improve productivity and resilience. Factors like dietary fiber, trace minerals, feed particle size, and bioactive compounds play critical roles, yet challenges remain. Integrated, data-driven interventions may offer sustainable solutions for livestock systems.

Animal agriculture is confronting a significant challenge: How to sustain animal health and productivity while reducing dependence on, or without antibiotics, especially antibiotic growth promoters (AGPs). The widespread and routine use of antibiotics in livestock has played a major role in the global rise of antimicrobial resistance (AMR), posing serious risks to both animal and human health.

A promising path forward through nutrition-driven strategies that promote gut health stands out. These approaches not only support animal well-being but also boost productivity and welfare by enhancing the gut’s natural defenses, improving nutrient absorption, and lowering disease risk. Nutrition-based solutions can also offer a sustainable alternative to antibiotics.

THE GUT MICROBIOME: A CORNERSTONE OF LIVESTOCK HEALTH
Managing the gut environment is essential for animal health and performance. Beyond digestion and nutrient absorption, it is home to a complex community of microorganisms—the gut microbiome—that significantly influence immune function, pathogen resistance, and overall well-being. A healthy microbiota creates a natural barrier against harmful bacteria through competition, regulating inflammation, and aiding nutrient metabolism. The gut is also the largest immune organ in poultry and livestock, containing gut-associated lymphoid tissue that detects and responds to pathogens.

FACTORS TO CONSIDER WHEN SELECTING FEED ADDITIVES
Enhancing gut health requires understanding the microbiome, immune function, nutrient absorption, and disease risk. This knowledge assists in the selection and integration of nutritional strategies and the potential incorporation of feed additives based on their specific modes of action. When evaluating additives, I keep several key factors in mind:

Targeted gut health benefits: Choose additives by their specific modes of action and desired outcomes, such as modulating gut microbiota, enhancing digestive enzyme activity, reducing pathogens, stimulating immunity, and improving gut barrier integrity.

Mode of action and synergy: Understanding how additives work—whether antimicrobial, anti-inflammatory, or antioxidant—and their potential synergistic effects helps optimize gut health. Recent research shows that AGPs’ primary mode of action is their anti-inflammatory effect rather than direct antimicrobial activity.

Physiological stage: Different life stages have unique gut microbiota and nutritional needs influencing additive choice. For example, young animals have a relatively simple, immature gut microbial population which is still undergoing colonization and succession and is more sensitive and susceptible to environmental influences and diet. Probiotics in young animals can help shape the initial establishment of a healthy and balanced gut microbiota, competitively excluding pathogens and promoting beneficial microorganisms. In contrast, mature animals have a well-established, stable, and complex microbial ecosystem that is more resilient and less responsive to external probiotic interventions.

Stability and delivery: Additives must remain stable during feed processing and storage in order to be delivered effectively to targeted sites in the gut.

Cost-effectiveness and producer goals: Always weigh the cost of additives against the expected improvements in health, performance, and antibiotic reduction.

Environmental and management conditions: Feed hygiene, litter quality, housing, and stress levels play a crucial role in gut health and must be managed alongside nutritional solutions to maximize their effectiveness.

NUTRITIONAL STRATEGIES THAT SUPPORT GUT HEALTH
I see several nutritional strategies that enhance gut health, including:
Conditionally essential amino acids (CEAAs): Their role becomes especially important when formulating low crude protein diets, which are increasingly common to reduce nitrogen excretion and environmental impact. Unlike essential amino acids, which must always be provided in diets, CEAAs are synthesized by animals but may be insufficient during stress or disease. They perform critical functions beyond basic protein synthesis. For example, cysteine and glycine contribute to glutathione production, a major antioxidant protecting gut cells. Serine and proline are key components of mucin, maintaining the gut mucus barrier’s structural integrity. With arginine it supports nitric oxide synthesis, an important immune signaling molecule.

Mycotoxins: They damage the gut barrier, making animals more susceptible to infections. A recent study in broilers demonstrated that the mycotoxin deoxynivalenol (DON) increases antibiotic-resistant bacteria and resistance genes in gram-positive bacteria, promoting horizontal gene transfer and potential spread of resistance traits. Regions contaminated by mycotoxins often overlap with those harboring high levels of antibiotic resistance, suggesting these threats coexist in the same environment.

Moreover, many mycotoxins and antibiotics contain fungal secondary metabolites, with similar structures and metabolism, potentially leading to cross-resistance. Bacteria exposed to mycotoxins can develop resistance mechanisms that also protect against antibiotics, encouraging the co-selection and spread of resistance genes.

While I recognize that mycotoxin binders and deactivators play an important role in managing mycotoxins, I believe they should be part of a broader, integrated approach whenever possible. On the farm, I emphasize good agronomic practices like crop rotation, selecting resistant hybrids, and minimizing mechanical damage during harvest to reduce fungal contamination early on. After harvest, I focus on proper drying and carefully controlling storage conditions, particularly moisture levels and temperature, as these factors are critical to preventing mycotoxin formation.

Dietary Fiber: Once considered merely a diluent and often overlooked and misunderstood, it is now recognized as an essential component for gastrointestinal development in poultry and pigs. It is known that insoluble fiber has the ability to remain in the gizzard for a longer period of time, enhancing muscular development and function, and prolonging feed retention time. This slower transit improves nutrient digestion and reduces toxin buildup, while for soluble fiber, it tends to increase intestinal viscosity, potentially decreasing nutrient absorption. Enzyme supplementation in animal diets can selectively break down insoluble and soluble dietary fiber fractions, reducing their antinutritive effects while releasing beneficial fermentable substrates that support gut microbial balance and overall gastrointestinal health.

Dietary fiber does hold advantages and moderate levels of insoluble fiber are recommended for broiler, layer, and pig diets. Common sources include wheat bran, rice bran, oat hulls, purified lignocellulose, and specialized crude fiber concentrates. Strategic use of these ingredients can enhance gut health by promoting intestinal motility, supporting microbial diversity, and contributing to improved digestive resilience.

In the hindgut, dietary fiber is fermented by microbes to produce short-chain fatty acids (SCFAs) like butyrate, acetate, and propionate. These SCFAs serve as energy sources for gut epithelial cells, strengthen gut barrier integrity, and help reduce inflammation. While soluble fibers ferment more rapidly, insoluble fibers also undergo significant fermentation, shaping the gut microbiome and supporting gut health in both poultry and pigs.

Anti-Nutritional Factors (ANFs): Certain feed ingredients may contain compounds such as protease inhibitors, tannins, lectins, phytates, saponins, and gossypol. These components can impair protein digestion, mineral absorption, and overall nutrient uptake, causing nutritional stress that weakens the immune system. This stress triggers bacteria to form biofilms, which are protective communities that shield microbes from antimicrobial agents. Biofilms also facilitate close contact between bacteria, promoting the transfer of resistance genes and accelerating AMR.

Additionally, many ANFs induce gut inflammation and oxidative damage, disrupting the intestinal barrier and upsetting gut microbiota balance. This imbalance favors colonization by pathogenic and antibiotic-resistant bacteria. Managing and reducing ANFs through improved feed processing and careful ingredient selection can minimize these negative effects.

Medium-Chain Fatty Acids (MCFAs): The ones that contain 6 to 12 carbon atoms, are particularly valuable because they are rapidly absorbed and metabolized by intestinal cells, offering quick, efficient energy that supports intestinal lining repair—a vital process for maintaining the integrity of the intestinal mucosal barrier.

By promoting epithelial cell regeneration and preserving mucosal integrity, MCFAs strengthen the gut barrier, preventing harmful pathogens and toxins from entering the bloodstream, thereby reducing inflammation and infection risk. They also help balance the gut microbiome by inhibiting pathogenic bacteria and encouraging beneficial microbes, which enhances digestion and nutrient absorption.

Moreover, MCFAs modulate immune responses by lowering pro-inflammatory cytokines such as IL-6 and IL-8, supporting mucosal immunity and natural disease defenses.

Research has shown the antimicrobial effectiveness of monolaurin, derived from lauric acid, is dependent on its molecular structure. In the alpha configuration, monolaurin is more functional because it can effectively insert itself into the lipid-based outer membranes of enveloped viruses and Gram-positive bacteria. This helps break down the pathogen’s protective membrane, causing it to become destabilized, more permeable, and eventually disintegrate. In contrast, the beta form is less stable and biologically active, with a limited ability to disrupt these pathogen membranes.

For example, in inhibition assays against Escherichia coli and Streptococcus suis, pre-emulsified α-monolaurin at 600ppm and 1200ppm achieved inhibition ratios above 87% and 92%, respectively, whereas monomeric α-monolaurin showed minimal inhibition.

Black Soldier Fly Larvae (BSFL): They lack an adaptive immune system and do not produce antibodies. Instead, they rely on a diverse array of antimicrobial proteins (AMPs) and peptides for pathogen defense, with over 57 AMPs identified. These AMPs exhibit broad-spectrum activity against bacteria, fungi, and viruses.

BSFL’s AMPs have gained my attention as promising antibiotic alternatives in animal feed, helping reduce antibiotic use. Their robust innate immune factors enable them to thrive in microbe-rich environments such as decomposing waste.

Additionally, about 47% of BSFL’s fatty acid profile is lauric acid, a much higher level than other insects, further enhancing their antimicrobial properties.

Feed Particle Size: Fine feed particles (<0.4mm) lead to faster feed passage and lower exposure to acidic conditions in the gizzard or stomach. This environment allows pathogens like Clostridium perfringens, E. coli, and Salmonella to survive and multiply in the small intestine.

In contrast, coarser particles (1–1.2mm) improve gut health in pigs and poultry by extending feed retention time in the stomach or gizzard, increasing exposure to acidic conditions. Coarse particles also boost SCFA production—especially propionic and butyric acids—in the hindgut, which support gut barrier integrity, lower intestinal pH, and inhibit harmful bacteria.

While some fine particles are necessary in pelleted feeds to ensure starch gelatinization and pellet quality, excessively large particles (>1.2mm) should be avoided as they reduce available surface area for enzymatic digestion, decreasing feed efficiency.

Trace Minerals: They are vital—not just for growth and reproduction but also for gut health. Minerals like zinc, copper, manganese, iron, and selenium influence gut flora, structure, and function, including regulation of gene expression for tight junction proteins.

These minerals, particularly in organic form, improve intestinal morphology by increasing villus height and the villus-to-crypt ratio, indicators of better nutrient absorption and digestive efficiency. They also maintain the intestinal barrier’s integrity, preventing leakage and infection.

Furthermore, trace minerals modulate immune responses in the gut by reducing excessive inflammation and enhancing pathogen defense. For example, zinc can lower the cellular levels of pro-inflammatory cytokines. They also support antioxidant enzyme activity, protecting gut cells from oxidative stress, reducing damage, and aiding recovery from disease.

Diagnostics: They complement nutritional strategies aimed at improving gut health. Rapid analysis of key biomarkers related to productivity, gut damage, and microbial balance—using simple, non-invasive samples like cloacal or rectal swabs—enables early detection of gut health issues before clinical symptoms emerge.

This timely insight allows prompt targeted interventions, maintaining a balanced and resilient microbiome that naturally reduces disease risk. Healthier gut environments make animals less vulnerable to infections.

Overall, this data-driven approach empowers smarter and faster decision-making on farms across nutrition, management, and welfare. These informed actions contribute significantly to minimizing antimicrobial use and combating antibiotic resistance, driving sustainable and productive livestock systems.

CHALLENGES AND CONSIDERATIONS
In shifting away from antibiotics toward nutrition-based gut health, I am mindful of the challenges involved. Nutrition alone isn’t a cure-all. Achieving antibiotic-free production requires a holistic approach, combining strict biosecurity, improved management, and effective vaccination to sustain animal health and resilience.

During this transition, I expect some temporary setbacks as production systems adapt. Patience and ongoing adjustments are crucial. Additionally, I suggest to tailor nutritional interventions to species differences, age, diet composition, and management conditions for maximum effectiveness.

FINAL THOUGHTS
The animal agriculture sector’s reliance on antibiotics is unsustainable in light of the global threat posed by AMR. While challenges remain, I’m convinced that nutrition-driven gut health solutions present a practical, science-based alternative to sustainably protect animal and human health, while enhancing productivity and welfare.

Based on long-term experience across many countries, I can confidently say that antibiotic-free production is achievable without sacrificing productivity or profitability. Success depends on collaborative efforts, shared responsibility, and continuous innovation.

Central to this success are targeted nutritional strategies that promote gut health, optimize nutrient absorption, and enhance immune function. By adopting comprehensive, nutrition-driven approaches, producers can ultimately reduce reliance on antibiotics while maintaining animal performance and welfare, ultimately building resilient, sustainable animal agriculture systems.

About Edward Manchester
As the Global Commercial Director of Ecolex Animal Nutrition, Edward Manchester has nearly 30 years of international experience, including early career roles in Europe and two decades leading innovation in Asia. He is recognized for pioneering advanced feed additive technologies and precision nutrition strategies that drive feed efficiency, animal health, and sustainability across global markets.