In animal nutrition, the difference between prebiotics and probiotics lies in their function and composition. Probiotics are live microorganisms added directly to feed to introduce beneficial bacteria into the animal’s gut. Prebiotics are non-digestible dietary fibres that serve as food for the beneficial bacteria already present in the gut, helping them grow and multiply.
Prebiotics vs. Probiotics in animal nutrition
| Feature | Prebiotics | Probiotics |
| What they are | Nondigestible dietary fibres, such as fructo-oligosaccharides (FOS) and mannan-oligosaccharides (MOS). | Live, beneficial microorganisms, including specific strains of bacteria (e.g., Lactobacillus, Bacillus) and yeast (e.g., Saccharomyces cerevisiae). |
| How they work | Serve as a selective food source for beneficial gut bacteria. They are fermented in the large intestine (monogastrics) or rumen (ruminants) to produce beneficial metabolites like short-chain fatty acids (SCFAs), which provide energy and improve gut health. | Modulate the gut microbiota by directly adding beneficial bacteria. They also compete with harmful pathogens for nutrients and binding sites on the intestinal wall, inhibiting their growth. |
| Benefits in animals | • Enhance nutrient absorption: Increase the bioavailability of minerals like calcium and magnesium. • Improve gut barrier function: Promote the production of protective mucus. • Reduce pathogen risk: Support a healthy gut environment that is less hospitable to disease-causing microbes. • Provide energy: Fermentation produces short-chain fatty acids, which are used as an energy source. • Enhance immunity: Help develop and strengthen the immune system. | • Boost digestion: Produce digestive enzymes and increase nutrient digestibility and feed conversion efficiency. • Increase immunity: Regulate immune responses to reduce inflammation. • Inhibit pathogens: Produce antimicrobial compounds and occupy adhesion sites to prevent harmful bacteria from colonizing the gut. • Reduce stress: Lessen the impact of stress, such as during weaning or transportation. • Improve meat and milk quality: Impact carcass quality and milk composition. |
| Application in animals | Often derived from plant sources or agricultural waste and included in feed for various animals, including poultry, swine, and calves. | Used as a feed additive or supplement in various livestock to help manage gut health and reduce the need for antibiotics. |
A common analogy to explain the microbiome, pre- and probiotics is as follows:
- The Garden represents the microbiome, a complex system of trillions of microorganisms.
- The Seeds represent probiotics, the beneficial live bacteria consumed.
- The Fertilizer represent prebiotics, the specialized dietary fibres that nourish and stimulate growth of beneficial bacteria in the gut.
We have discussed the microbiome in Blog Pos #3. Let’s focus more on Pre- and Pro-biotics.
Prebiotics: The Fertilizer
In animal nutrition, the analogy of prebiotics as “fertilizer” effectively describes their function in cultivating a healthy and robust gut microbiome. Rather than adding new microorganisms like probiotics, prebiotics work by providing specialized, non-digestible nutrients that selectively stimulate the growth and activity of beneficial microbes already present in an animal’s gastrointestinal tract.
This is especially critical considering increasing restrictions on antibiotics used as growth promoters, making prebiotics a natural and sustainable alternative for promoting animal health and productivity.
How prebiotics function as “fertilizer” for the gut microbiome
The primary mechanisms through which prebiotics benefit animal health include:
- Selective fermentation: Prebiotics are dietary fibres and oligosaccharides (like FOS and MOS) that cannot be broken down by the host animal’s digestive enzymes. They pass undigested to the hindgut (the large intestine in monogastrics or the rumen in young ruminants), where beneficial bacteria ferment them. This process creates a favourable, symbiotic environment for microbes like Lactobacillus and Bifidobacterium to thrive.
- Production of short-chain fatty acids (SCFAs): As the beneficial bacteria ferment the prebiotics, they produce SCFAs such as butyrate, acetate, and propionate. These SCFAs are a critical energy source for the intestinal cells and play a vital role in maintaining the integrity of the gut lining. A stronger gut lining improves nutrient absorption and acts as a barrier against pathogens.
- Suppression of pathogenic bacteria: The fermentation of prebiotics lowers the pH of the gut environment, creating unfavourable conditions for harmful bacteria like Salmonella and E. coli. Certain prebiotics, such as mannan-oligosaccharides (MOS), can also bind directly to pathogens and carry them out of the digestive tract.
- Modulation of the immune system: By promoting a healthy gut environment, prebiotics help regulate and strengthen the animal’s immune system. This makes the animal more resilient to disease, particularly during stressful periods like weaning or transportation.
Application across animal species
The “fertilizer” approach is valuable in different animal farming systems:
- Monogastric animals (poultry and swine): In these animals, prebiotics are added to feed, particularly during the vulnerable post-weaning phase, to reduce intestinal dysbiosis and improve growth performance.
- Pre-ruminant animals (calves and lambs): Since young ruminants have undeveloped rumens, they are highly dependent on dietary prebiotics to establish a healthy intestinal flora and combat common issues like diarrhoea.
- Ruminants (cattle, sheep): While a mature rumen produces its own microbes, prebiotics are still used to modulate the microbial populations and enhance the fermentation of complex fibres, which can improve feed efficiency and reduce methane emissions.
Probiotics: The Seeds
In animal nutrition, the analogy of probiotics as “the seeds” is a powerful way to explain their function within the gut microbiome. Probiotics are living microorganisms, such as beneficial bacteria and yeasts, which are intentionally introduced into an animal’s digestive tract to populate the gut with a thriving community of beneficial flora.
This is especially critical in young animals, like calves and piglets, whose gut microbiomes are underdeveloped and susceptible to harmful pathogens. Introducing a diverse array of probiotic “seeds” early in life can help establish a robust gut environment that supports long-term health and performance.
- Initial colonization: When live probiotic microorganisms are added to an animal’s feed, they are introduced into the gastrointestinal tract, where they begin to colonize and grow, much like seeds taking root in soil.
- Competitive exclusion: Once established, these beneficial bacteria compete with harmful, pathogenic bacteria (like Salmonella and E. coli) for nutrients and binding sites on the intestinal wall. This process, known as competitive exclusion, helps prevent the growth and spread of disease-causing microbes.
- Restoring balance: Probiotics are particularly useful after an animal has experienced stress, disease, or antibiotic treatment, all of which can disrupt the natural balance of gut microbes. The probiotics help to restore the microbial balance and promoting a healthier intestinal ecosystem.
- Producing beneficial compounds: As probiotics grow and proliferate, they produce antimicrobial substances, such as organic acids and bacteriocins, that directly inhibit the growth of pathogens. They also aid in the digestion of nutrients, thereby improving the animal’s growth, feed efficiency, and overall performance.
Synergistic effect of Synbiotics
The combined use of prebiotics and probiotics is known as a synbiotic. In animal nutrition, synbiotics leverage the synergistic effect of both components to enhance animal health and productivity. The prebiotic component feeds and selectively promotes the growth of the beneficial probiotic bacteria, leading to a more robust and effective gut microbiome, improving the animal’s overall health and productivity.