Prebiotics and Probiotics: What's the Difference?
Changing consumer preferences, combined with regulatory shifts, have altered the landscape poultry producers use to evaluate their feed additive choices. Prebiotics and probiotics are increasingly popular choices, but the difference between the two is not always fully understood.
While complementary to each other, prebiotics and probiotics are not necessarily interchangeable in a diet, nor are they the same in how they affect gut microbes. They feature different modes of action and stem from different origins.
They may be used in animal diets independently or in combination to help producers accomplish the desired outcomes of enhanced animal health and productivity.
Nor are they new. For instance, the use of probiotics in farm animals dates back 75 years, but in the 1960s for the first time it was demonstrated that Lactobacillus could significantly stimulate growth in pigs.1
Prebiotics
Prebiotics act as a food source for the good bacteria that are already living in the gastrointestinal (GI) tract and have been shown to support animal health and performance.
More formally, a prebiotic is a specialized, non-digestible carbohydrate that beneficially sustains the good bacteria already in the GI tract. A prebiotic is not a microorganism. It is a sort of nourishment source for existing bacteria, allowing the existing normal colony within an animal’s gut to grow naturally and reproduce.2
Prebiotics may be obtained from several sources, including certain yeast cell walls such as Saccharomyces cerevisiae.
Prebiotics are complex sugars (usually oligomers), but not all sugars are prebiotics. Many sugars are digestible by the animal and are used as an energy source.
However, chains of the sugar mannose, for example, are not readily absorbed by poultry and livestock but can serve as a nutrient source for bacteria residing in the GI tract. Mannose as a simple sugar or as a chain of molecules (mannan oligosaccharides) also may allow certain pathogens to bind to it rather than to the intestinal cell of the animal, reducing the severity of infections.
Several prebiotic compounds have been incorporated into animal nutrition, including:
- Non-digestible oligosaccharides such as fructooligosaccharide (FOS)
- Non-digestible mannan oligosaccharides (MOS)
Probiotics
The word “probiotic” comes from the Greek words “pro” and “biotic,” meaning “for the life.”
Probiotics have sometimes been referred to as “direct-fed microbials.” Targeted microbial solutions is a more descriptive term. These are proprietary strains of Bacillus selected to combat the specific challenges in a farm’s Microbial Terroir™—which includes the environment, soil, animals and weather on a specific farm location.
These good strains of bacteria help combat harmful pathogens that are impacting animals’ performance and are a live microbial feed additive that beneficially affects the host animal by improving its intestinal balance.
In short, probiotics are the “good” bacteria that live in the animal’s GI tract. They work by competitive exclusion—that means when adequate populations of probiotic bacteria are present, they reduce the ability of pathogenic bacteria to get out of control and overwhelm the host. Simply, they crowd pathogens out. They also work by specifically inhibiting pathogenic growth.
The joint Food and Agriculture Organization of the United Nations (FAO) and World Health Organization (WHO) Working Group defines probiotics as “live microorganisms which, when administered in adequate amounts, confer a health benefit on the host.”
Probiotics help to prevent and control gastro-intestinal pathogens and/or improve the performance and productivity of production animals through various mechanisms. Closely related strains may differ in their mode of action.3
Interest in probiotics (and prebiotics) is rising steadily in relation to increasing concern and regulatory control regarding the sub-therapeutic use of antibiotic growth promoters in animal feed. Plus, the WHO group notes that there seems to be a greater appreciation of the role of the microbial ecology of the GI tract in determining animal productivity.
Livestock probiotics commonly feature various strains of Bacillus, Lactobacillus, Enterococcus and Saccharomyces yeast. These “good” bacteria have battled it out with pathogenic bacteria since time began. There is much yet to learn about these interactions, but it is understood that certain strains of Bacillus have been proven to decrease growth of certain strains of pathogenic bacteria including E. coli, Clostridium, Streptococcus and Salmonella.
Further, probiotics act as a regulator for the immune system. For instance, microbial communities can support the animal's defense against invading pathogens by stimulating gastrointestinal immune response. This may aid the development of the immune system by stimulation of the production of antibodies and increased white blood cell activity.4
Synbiotics
Lastly, there’s one more category to consider.
Oftentimes probiotics and prebiotics are combined into feed additives to compound synergistic effects. These are referred to as synbiotics.
As prebiotics furnish better conditions for probiotics to expand, the colonies of these “good” bacteria are maintained. Studies have shown that by using the benefits of both prebiotics and probiotics, the number of desirable bacteria in the digestive system increases and demonstrates positive effects on health status.2
Ultimately, prebiotics, probiotics and combinations thereof hold tremendous potential to positively influence animal health and productivity—and the ability of livestock and poultry producers to get their daily jobs done in the most efficient and effective manner.
Hippocrates, Greek philosopher and the father of medicine, was millennia ahead if his time when he wrote: “Let food be thy medicine and medicine be thy food.”1
1 ASML A, Agazzi A, Invernizzi G, Bontempo V, Savoini G. The Beneficial Role of Probiotics in Monogastric Animal Nutrition and Health. J Dairy Vet Anim Res 2015;2(4):00041. DOI: 10.15406/jdvar.2015.02.0004.
2 Alloui MN, Szczurek W, Świątkiewicz S. The Usefulness of Prebiotics and Probiotics in Modern Poultry Nutrition: A Review. Ann Anim Sci 2013;13(1):17-32. DOI: 10.2478/v10220-012-0055-x.
3 FAO. 2016. Probiotics in animal nutrition – Production, impact and regulation by Yadav S. Bajagai, Athol V. Klieve, Peter J. Dart and Wayne L. Bryden. Editor Harinder P.S. Makkar. FAO Animal Production and Health Paper No. 179. Rome. Available at: http://www.fao.org/3/a-i5933e.pdf. Accessed October 31, 2017.
4 Yirga H. The Use of Probiotics in Animal Nutrition. J Probiotics and Health 2015;3:132. Available at: https://www.omicsonline.org/open-access/the-use-of-probiotics-in-animal-nutrition-2329-8901-1000132.php?aid=59945 Accessed October 31, 2017.
