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Gastrointestinal Microbiota Balance and Livestock Health

An animal's gastrointestinal (GI) tract is critical to its health and wellbeing. It's obvious that, without it, the animal would be unable to absorb nutrients. However, the role of the GI tract extends far beyond this function. Dr. Ryan N. Dilger, University of Illinois Animal Sciences professor, explains, "about 70% of immune cells are associated with the intestines in some way. That's because we have a large surface area with a layer of enterocytes in direct contact with the outside world. So, it makes sense that we have a lot of the immune resources that are centralized there in the intestine." One key to those immune resources is the balance of microbiota in the GI tract.

Benefits of a balanced microbiota

The microbiota is a set of specific microorganisms found within a given environment — such as the GI tract. The microorganisms that make up this microbiota can vary based on several factors including the species, the environment and the diet that's being provided, according to Dilger. While there are changes in these bacteria over time, "good" bacteria provide defense to the animal by:

  • Working to reduce harmful intestinal pathogens: The microbiota can help block the attachment and colonization of most invading enteric pathogens including Salmonella and Escherichia coli.
  • Improving host nutrition: Without a balanced microbiota, nutrients found in the diet will not be fully broken down and utilized by the body. In addition, the microbiota produces useful metabolic substrates such as vitamins and short-chain fatty acids.
  • Bolstering immunity: A beneficial microbial community plays a key role in maintaining physiological homeostasis, altering the immune system, and influencing organ development and metabolism.1

Dilger explains why immunity is so critical, "when an animal is healthy, it takes relatively few resources to maintain the immune system. However, when animals encounter an immune challenge or become sick, immunity becomes the number one priority. While this is absolutely necessary, it comes at the expense of muscle accretion and other performance priorities."

Problems stemming from a disrupted microbiota

If the composition or function of this microbiota becomes disrupted (dysbiosis), it can affect the immunity and overall health of the host animal. Dysbiosis can occur for many reasons, for example, because the animal has been treated with antibiotics. "A depletion of commensal bacteria means that they are not there as part of that first line defense to stop pathogenic bacteria like Salmonella," says Dr. Dilger. This can cause a breakdown of the epithelial barrier and result in inflammation. "Eventually these pathogens may actually get into the bloodstream and cause sepsis," Dilger explains. "So, maintaining these commensal bacteria, or microbiota, serves to help prevent some of these breaches."

While sepsis is a severe outcome of a disrupted microbiota, animals can suffer a whole host of consequences if microbiota balance to internal tissues isn't maintained — including, but not limited to, practical productivity implications like decreased feed intake, slowed muscle tissue development and internal inflammation. Even subclinical infections can lead to a loss in performance.

Potential Outcome

Intervention to rebuild and stabilize microbiota

With age, a healthy animal's microbiota develops until it reaches a relatively stable phase. With a disrupted microbiota, we may not see it reach the stable point without intervention. "This is where many nutritional technologies are going to come in," says Dilger. "We may use an intervention like prebiotics or probiotics to intervene in the life of that animal. And in some way, try to correct that disruption to produce a microbiota composition that is more typical for that species or individual animal."

Ryan N. Dilger Pull Quote

Let's take a closer look at probiotics and prebiotics and how they work.

Probiotics are live microorganisms, usually strains of beneficial bacteria, or "good bugs." Certain probiotics only focus on helping maintain the microbial balance and diversity in the gut, while others also help reduce the number of pathogens.

Prebiotics are carbohydrates, mostly fiber, used by probiotics and good bacteria as fuel. To increase the quantity of good bacteria within the gut or help offset the imbalance of pathogenic bacteria, both prebiotics and probiotics are needed.2

An ideal probiotic should be non-pathogenic, resist acidic gut conditions, produce antimicrobial compounds, improve commensal (or helpful) bacterial growth, modulate the immune response, improve animal performance, and withstand feed processing conditions.3

Dive deeper into the four 'biotics: Pre-, pro-, post- and synbiotics

Learn more about the right support for your animals

"There are a number of relationships that we can identify between the diet, the microbiota and the immune system of the host, and that this is going to directly influence both animal growth development and wellbeing," says Dilger. Therefore, supporting a healthy microbiota by supplementing feed with prebiotics and probiotics can also help improve the health, wellbeing and performance of animals. Contact your Kemin representative to find the right nutrition solutions for your specific animals and health issues.

Hear more from Dr. Dilger and other gut health experts at




1Oakley, B. B., et al. 2014. The chicken gastrointestinal microbiome. FEMS Microbiol. Letters. 360:100-112.
2High J. The Importance of Equine Prebiotics and Probiotics for Gut Health. Quarter Horse News, July 19, 2021.
3Antibiotic Alternatives in Managing Gut Health. Kemin.

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