Every day, a broiler’s intestine processes several times its body weight in feed and water, encounters billions of microorganisms, responds to environmental stress, and continuously decides what enters the body and what remains outside.

In many ways, the gut functions as a customs checkpoint, security system, digestive factory, and immune headquarters—all at the same time.

In fact, nearly 70% of the bird’s immune cells are associated with the gastrointestinal tract, making it a key player in both health and performance. The remarkable aspect is that when the gut is functioning well, nobody notices it. When it begins to fail, everybody notices the consequences.

The Modern Poultry Bird: Built for Speed
Today’s broiler is a biological marvel. Through decades of genetic selection, modern birds reach market weight faster and more efficiently than ever before.
However, this achievement comes with a hidden challenge.

The digestive tract has become one of the most critical performance-limiting organs in poultry production. Every gram of feed must be digested, absorbed, and converted into muscle within an increasingly compressed production cycle.

Twenty years ago, a small reduction in nutrient absorption might have gone unnoticed. Today, even minor intestinal inefficiencies can translate into measurable losses in body weight gain, feed conversion ratio, and profitability. Modern birds can no longer afford a lazy gut.

The Gut Is Constantly Making Decisions
Traditionally, we think of the intestine as a nutrient absorption organ.
In reality, the gut is making thousands of biological decisions every second.

– Should nutrients support growth or immunity?
– Should a microorganism be tolerated or eliminated?
– Should energy be invested in production or defense?
– Should the intestinal barrier remain open for absorption or tighten to prevent invasion?

These microscopic decisions ultimately determine flock performance.
In many ways, poultry production is not simply about feeding birds—it is about influencing the decisions being made within the gut.

The Hidden Cost of Inflammation
One of the most important concepts emerging in poultry science is that inflammation carries a nutritional cost.
Whenever the intestine encounters stress from pathogens, mycotoxins, heat, poor litter quality, or microbial imbalance, the immune system becomes activated.
The immune response is essential for survival, but it is expensive.
Energy that could support growth is redirected toward immune activity.
Amino acids that could build muscle are utilized to produce immune proteins and inflammatory mediators.
Vitamins and minerals become involved in tissue repair and antioxidant defense.
The bird continues eating, yet a significant proportion of nutrients may no longer be contributing to production.
This phenomenon is often referred to as the “hidden feed cost” of inflammation.

The Silent Performance Thief
One of the greatest misconceptions in poultry production is that intestinal problems always produce visible symptoms.
– Not necessarily.
– Many flocks show normal feed intake, acceptable mortality, and no obvious disease outbreaks. Yet they consistently fail to achieve target performance.
– A slight reduction in nutrient absorption.
– A minor microbial imbalance.
– A low level of intestinal inflammation.
– A subtle increase in intestinal permeability.
Individually these changes may appear insignificant. Collectively they can result in substantial economic losses. This is why gut health is increasingly viewed not as a disease issue but as a performance issue.

The Microbial Workforce Inside Every Bird
Perhaps the most fascinating discovery in recent years is the realization that birds are never truly alone.
The digestive tract contains trillions of microorganisms collectively known as the gut microbiome.
These microbes help digest feed ingredients, produce beneficial metabolites, support intestinal development, influence immune responses, and compete with harmful bacteria.
Some scientists now describe the microbiome as an additional organ because of its profound influence on bird health.
This raises an interesting question:
Are we feeding the bird, or are we feeding its microbiome?
The answer is both.
The future of poultry nutrition may depend as much on managing microbial populations as on balancing nutrients.

Heat Stress: The Gut’s Greatest Enemy
In many poultry-producing regions, heat stress has become one of the most significant challenges affecting gut health.
High environmental temperatures reduce blood flow to the intestine, increase oxidative stress, and compromise intestinal barrier integrity.
As a result, harmful bacterial toxins can cross the intestinal wall and trigger inflammation.
Often the first casualty of heat stress is not growth—it is gut integrity.
This may explain why heat-stressed flocks frequently show poorer FCR, increased wet litter, reduced nutrient utilization, and greater disease susceptibility.
As global temperatures continue to rise, protecting gut health during periods of heat stress will become increasingly important.

The Gut in the Antibiotic-Free Era
The poultry industry is rapidly transitioning toward antibiotic-free and reduced-antibiotic production systems.
While this shift addresses consumer concerns and regulatory requirements, it has also increased attention on intestinal health.
Without routine antibiotic growth promoters, producers must rely on alternative strategies to maintain gut stability.
Probiotics, prebiotics, β-glucans, mannan oligosaccharides (MOS), organic acids, phytogenic compounds, and postbiotics are increasingly being used to support intestinal resilience and microbial balance.
The focus is shifting from killing pathogens to creating an intestinal environment where beneficial microbes and the host can thrive together.

More Birds or More Protein?
The global poultry industry is not being asked to produce more birds.
It is being asked to produce more protein.
As the world’s population grows and consumers increasingly seek affordable animal protein, poultry production continues to expand. Industry projections estimate the sector will grow at a CAGR of approximately 5–7% over the coming years.

But growth alone is not enough.
Producers are expected to deliver more meat with fewer resources, lower feed costs, and a smaller environmental footprint.
This means that every gram of feed matters more than ever before.
And that brings us back to the gut.
Because the difference between feed consumed and protein produced is ultimately determined by the efficiency of the digestive system.

The Future Begins in the Gut
For decades, poultry production focused on genetics, nutrition, and disease control.
The next frontier may be intestinal resilience.
Future improvements in productivity will likely come from better management of inflammation, enhanced barrier integrity, optimized microbiomes, and improved nutrient efficiency within the gastrointestinal tract.
The question may no longer be:

“How much feed did the bird consume?”

Instead, the more important question may be:
“How much of that feed actually became growth?”
The answer lies within the gut.
Not because it is merely another organ, but because it is the organ that determines how effectively all the others perform.
In an era of narrow margins, rising feed costs, heat stress, and antibiotic-free production, the healthiest gut may ultimately become the most valuable asset in the poultry house.

Dr. Natthanan Nukitrangsan,
Ph.D, Feed Nutritionist & Technical Consultant
CP BIO

Introduction
Imbalances in the intestinal microbiota are linked to the development of various diseases. As a result, there has been growing interest in using prebiotics, probiotics, and postbiotics to modulate the gut microbiome. Postbiotics refer to substances released or produced through the metabolic activity of microorganisms that exert beneficial effects on the host, either directly or indirectly. Since postbiotics do not contain live microorganisms, the risks typically associated with their consumption are significantly reduced.

In this review, we critically examine current literature on postbiotics, focusing on their mechanisms of action and potential applications in performance trials. We highlight their distinct benefits compared to live probiotics, with the goal of maximizing the effectiveness of postbiotics in target animals. The review explores their key components and advantages related to diet and gut health, emphasizing their role in supporting animal production—particularly in poultry. Relevant studies are referenced to illustrate the immunomodulatory, antimicrobial, anti-inflammatory, and antioxidant properties of postbiotics, as well as their overall impact on productivity and health in animal systems.

How to distinguish postbiotics and their benefits compared to live probiotics?

Postbiotics are metabolic by-products produced by bacteria (exogenous postbiotics). They include non-viable bacterial components and substances such as short-chain fatty acids (SCFAs), peptides, bacteriocins, proteins, and amino acids, all of which can confer health benefits to the host. Unlike probiotics, postbiotics are more stable during feed processing and under various environmental conditions. This enhanced stability, along with their enriched nutrient profile, makes postbiotics a promising alternative to probiotics in animal feed applications.

The use of postbiotics as a tool for improving the health of livestock and poultry shows great promise, owing to their numerous benefits and several advantages over probiotics and prebiotics. As metabolic byproducts or components derived from probiotic bacteria, postbiotics are less sensitive to environmental factors such as temperature, pH, and processing methods (Hossain et al., 2021). This enhanced stability allows them to retain their functional and beneficial properties over time, making them well-suited for diverse applications in animal health and nutrition (Thorakkattu et al., 2022).

Furthermore, we provided the information of postbiotics that can offer more advantages than live probiotics; for instance, (Rafique et al., 2023),

(a) Live probiotics may struggle to adhere to the gut mucosa due to the presence of a mucous layer that limits direct contact between bacteria and the epithelial surface. In contrast, postbiotics can more easily penetrate this mucous layer.
(b) Postbiotics pose no risk of infection from bacterial translocation from the intestinal lumen into the bloodstream, which is particularly important for immunocompromised or susceptible individuals. Additionally, they do not carry the risk of acquiring or transferring antibiotic resistance genes.
(c) Postbiotics offer practical advantages—they are easier to dose, transport, standardize, and store. Moreover, they have significant potential to support intestinal barrier function and may serve as an effective alternative to probiotics (Liu et al., 2023).

The benefits of postbiotics for gut health.
Postbiotics can inhibit the growth of pathogens and strengthen gut barrier function through the action of short-chain fatty acids (SCFAs). For instance, butyrate serves as an energy source for colon epithelial cells and the intestinal mucosa, thereby supporting gut integrity and reducing intestinal permeability.
In addition to enhancing gut barrier function, butyrate plays a role in immunomodulation and exhibits anti-inflammatory effects while helping to improve growth performance, as illustrated in Figure 1.

Figure 1: Functions of postbiotics

Butyric acid has demonstrated in vitro antimicrobial activity against both Gram-positive bacteria (e.g., Enterococcus faecalis, Clostridium perfringens, Streptococcus pneumoniae, Streptococcus suis) and Gram-negative bacteria (e.g., Escherichia coli, Salmonella enterica Typhimurium, Campylobacter jejuni) (Kovenda et al., 2019).

The mode of action of sodium butyrate involves its conversion to butyric acid, which can penetrate bacterial cell walls primarily through diffusion. Once inside the cell, butyrate induces cytoplasmic toxicity by lowering the intracellular pH. This acidification disrupts key metabolic processes, depletes energy reserves, and leads to the excretion of protons (H⁺), which further diffuse into the bacterial cell and contribute to toxicity. The increased proton concentration interferes with ATP synthesis by impairing the bacterial cell’s ability to maintain proton gradients essential for energy production and metabolism. Ultimately, the drop in pH and metabolic disruption result in bacterial cell death (Ahsan et al.,2016).

Maximize the effectiveness of postbiotics in target animals.
Based on researches, postbiotic can be able to target gut-brain axis influence on serotonin to improve growth performance (Sofie et al., 2021; Ishii et al.,2019), gut health and nutrient digestion (Ahmed et al., 2014; Kumar et al., 2014), antimicrobial (Mantziari et al., 2020; Fong et al., 2020), anti-inflammation and Immune-microflora balance (Torino et al., 2015; Miyazawa et al., 2015; Maghsood et al., 2018;) including postbiotic/probiotic as an alternative ATB/ZnO (Ali et al., 2023).

FermNutral® derived from the biological fermentation of the probiotic strain Clostridium butyricum, the main components of the product include amino acids, minerals, and beneficial metabolites classified as postbiotics. Rafique et al. (2023), writing in the Journal of Agriculture & Food Research, reviewed the principal classes of postbiotics with health-promoting effects:

1. Short-chain fatty acids (SCFAs) –
Butyrate supports gut integrity, reduces intestinal permeability, modulates immunity, exerts anti-inflammatory actions, and suppresses pathogens. In broilers, butyrate also raises apparent total‑tract crude‑fat digestibility and apparent metabolizable energy (AME), enhancing overall digestion and nutrient absorption.
2. Antimicrobial peptides (bacteriocins) – These peptides display activity against common pathogens, including Salmonella spp., Staphylococcus aureus, Yersinia enterocolitica, and Escherichia coli.
3. Quorum‑sensing (QS) interference – Certain postbiotics inhibit pathogen biofilm formation by disrupting QS signaling, thereby curbing colonization and persistence.
4. Polysaccharides (e.g., teichoic acids) – Contribute anti‑ inflammatory and antimicrobial effects, further supporting host health.
5. B‑complex vitamins, proteins, and amino acids – Provide additional nutritional and functional benefits that complement the antimicrobial and immunomodulatory actions of other postbiotic fractions.

Postbiotic product in poultry trials
FermNutral (FN)® is a postbiotic product consisting of non-living microorganisms (inactivated bacteria) or their components that provide health benefits to the host. It also includes byproducts of probiotic activity in the gut, such as fermentation metabolites.

The main ingredient is calcium butyrate, which makes up 50% of the product. Other components include short-chain fatty acids (butyric acid, acetic acid, propionic acid), 18 amino acids, vitamins (B1, B2, B5, B6, B12, folic acid, E, and K), and minerals (Ca, Fe, Zn, Na, Mg, P, Mn, Cr).

Based on our trial data and correlated research publications, we can confidently say that FN improves productive performance and reduces feed costs, which contributes to higher profits and effective solutions in animal production.

Typically, we focus on both performance and economic returns in animal production, especially for pigs, poultry, and aquatic species. Through extensive research conducted by CP BIO, we have found that using FN in aquatic animals such as Tilapia, Ruby fish, Penaeus vannamei, and Micropterus salmoides significantly enhances growth performance, feed efficiency, survival rates, and overall economic returns, as shown in Table 1.

Conclusions
FermNutral (FN) is a biological fermentation product derived from the probiotic strain Clostridium butyricum. It primarily contains short-chain fatty acids (SCFAs), especially butyrate, along with amino acids, minerals, and beneficial metabolites acting as postbiotics. Essentially, FN functions through the diet-gut-microbe axis to provide effective animal health solutions. Butyrate mainly supplies energy to the epithelial cells of the colon, improving digestion and nutrient absorption while controlling pathogens, maintaining immune balance, and reducing inflammation. Therefore, the multi-modal actions of FN help support gut function, enhancing animal performance and profitability.

References available on request.