Qu’est-ce que les prébiotiques et les probiotiques

What are Prebiotics and Probiotics ?

Written by Sophie Hébert Saulnier, veterinarian 

In the last few years , many new products have appeared on the market claiming to improve the digestive health of humans and animals alike. With so many to choose from, it may be difficult for consumers to choose the best product for their needs.

A unique ecosystem, encompassing many different species of bacteria, exists within the digestive system of each individual living being. Bacteria are microscopic organisms which can be found in all types of habitats including inside volcanoes, in the bottom of the ocean and also on our skin and in our gut. In fact, billions of bacteria can be found living on anindividual, be it animal orhuman.

Some species of bacteria are beneficial to our health. These are usually referred to as probiotics which means "for life". Other species of bacteria are pathogenic, meaning that they impact our health in a negative way and may cause illness.

Probiotic bacteria are present within the entire digestive system but most are in the small intestine where they serve a very important function. The population of bacteria living in our digestive system is known as our bacterial flora.

These bacteria are essential components of the digestive process, helping our body break down certain molecules so that they can be absorbed. They form a bacterial coating over our intestinal mucosa and act as a protective lining to keep bacterial pathogens from attacking the delicate lining of our intestinal wall.This protective layer of beneficial bacteria is called the biofilm. Probiotics improve the immune response by protecting our body from pathogenic bacteria and thus reduce the risk of illness.

Probiotics are generally combined with nutrients referred to as “prebiotics”. These are nutritive elements whose role is to serve as nutritional additives to probiotic bacteria.Prebiotic means “before life”. Providing nutrients to probiotic bacteria increases their numbers and variety and ensures a more diversified and abundant bacterial flora. Although bacteria can use a variety of substances as food, prebiotics are generally composed of certain types of fiber.

Probiotic supplements sometimes contain both the probiotic bacteria and the appropriate prebiotics. In such a case, the supplement will be more effective and it is therefore recommended to look for products containing both components.

  • 1.Hill, C; Guarner, F; Reid, G; Gibson, GR; Merenstein, DJ; Pot, B; Morelli, L; Canani, RB; Flint, HJ; Salminen, S; Calder, PC; Sanders, ME (August 2014). "Expert consensus document. The International Scientific Association for Probiotics and Prebiotics consensus statement on the scope and appropriate use of the term probiotic.". Nature reviews. Gastroenterology & hepatology.11 (8): 506–14.

Use of Probiotics

There are many ways in which probiotics can be used  in animals (and this also applies to humans!). The most common application for probiotics is for improving immune function.In fact, there are currently many studies researching this topic. The different uses for probiotics discussed in this article have not been scientifically proven for all companion animal species because only certain animal species have been studied to date.

The use of probiotics during antibiotic treatment reduces the risk of developing a secondary infection by restoring the bacterial flora destroyed by the antibiotics. Some of the bacteria in the probiotic supplement will be destroyed but those that survive will help repopulate the intestinal flora.

It is therefore important to give the probiotic supplement in a separate administration from the antibiotic in order to ensure that not all bacteria in the supplement will be destroyed by the antibiotic. It is recommended to wait at least 1 hour after the administration of the antibiotic before giving a probiotic in order to achieve a maximum survival rate of the beneficial bacteria found in the probiotic.

In addition, the probiotics stimulate the immune response, and act as an additional defense against the primary infection. Probiotic bacteria form a protective barrier inside the intestinal tract and help prevent pathogenic bacteria from making the animal sick. Some can even modify the environmentinside the intestine to make it more favorable to "good bacteria" and less hospitable to "bad bacteria". This increases the immune response to potential infections and reduces the chances of developing illness. Probiotics can also improve the immune response during vaccination, resulting in a better protection.

Probiotics are also used during and after antibiotic treatment. Antibiotics kill pathogenic bacteria which cause disease but also kill some of the beneficial bacteria. It is therefore important to recolonize the "empty" gut with new beneficial bacteria before pathogenic bacteria invade and cause a secondary infection.

Probiotics can help alleviate diarrhea and other symptoms of digestive disorder and can help reduce the severity and duration of the symptoms. When a digestive disorder is present, the normal gut flora is often disturbed and reestablishing this natural balance will help relieve symptoms in these cases.

Another way in which probiotics can be used in animals is when they are given to young animals to increase and accelerate growth. This is especially true of farm animals where they are used to increase the production rate but could also potentially be applied to other species since probiotics improve digestion and absorption of nutrients.

Beauchemin KA, Krehbiel CR, Newbold CJ (2006) Enzymes, Bacterial Direct-Fed Microbials and Yeast: Principles for Use in Ruminant Nutrition. In: Mosenthin R, Zentek J, Ebrowska TZ (Eds) Biology of Nutrition in Growing Animals.

Cho JH, Zhao PY, Kim IH (2011) Probiotics as a Dietary Additive for Pigs. Journal of Animal and Veterinary Advances 10 pp2 2127-2134.

Chaucheyras F and Durand H (2010) Probiotics in animal nutrition and health. Beneficial Microbes 1: 3-9.

Hiruta Yirga, (2015) The Use of Probiotics in Animal Nutrition, Journal of Probiotics & Health

Steiner T (2009) Probiotics in Poultry and Pig Nutrition: Basics and Benefits. The Poultry site.

Matteo A. Avella, Allen Place, Shao-Jun Du, Ernest Williams, Stefania Silvi, Yonathan Zohar, Oliana Carnevali.Lactobacillus rhamnosus Accelerates Zebrafish Backbone Calcification and Gonadal Differentiation through Effects on the GnRH and IGF Systems. PLoS ONE, 2012; 7 (9): e45572 DOI: 10.1371/journal.pone.0045572

H.H. Musa , S.L. Wu , C.H. Zhu , H.I. Seri and G.Q. Zhu (2009), The potential Benefits of Probiotics in Animal Production and Health, Journal of Animal and Veterinary Advances vol. 8, Issue 2, P.313-321

Rijkers GT, de Vos WM, Brummer RJ, Morelli L, Corthier G, Marteau P (2011). Health benefits and health claims of probiotics: Bridging science and marketing. British Journal of Nutrition. 106 (9): 1291–6

Hamid R. Haghighi,Jianhua Gong,Carlton L. Gyles,M. Anthony Hayes Babak, Sanei,Payvand Parvizi, Haris Gisavi,James R. Chambers, and Shayan Sharif, (2005). Modulation of Antibody-Mediated Immune Response by Probiotics in Chickens, Clin Diagn Lab Immunol. 2005 December; 12(12): 1387–1392 

Probiotic use during illness or antibiotic Therapy

When an animal is sick, it's immune system is very busy fighting against the infection. Probiotics can help the immune system fight the infection but also prevent the animal from developing a secondary infection.

The first way in which probiotics help fight infection is by forming a biofilm, or protective layer, along the wall of the intestine which prevents pathogens, or "bad bacteria" from causing illness. This is because the biofilm prevents the pathogenic bacteria from attaching to the lining of the gut thereby preventing them from entering the animal’s system. The pathogenic bacteria, unable to attach themselves, are forced through the gut and excreted by the body in the feces.

The second way in which probiotics help is by altering the environmental conditions inside the gut. Indeed, certain species of bacteria can modify the acidity, or pH level (balance between acid and alkaline), inside theintestinewhich improves the growthof other beneficial bacteria and slows the growth of bad bacteria. Some bacteria also produce molecules that inhibit the growth of pathogens, allowing more room for other beneficial bacteria to grow.

Probiotic bacteria also improve immune responseby playing a regulatory role on the immune system. This is referred to as “immunomodulation “. The bacteria act on certain types of cells that are involved in immune function.The use of probiotics during vaccination enhances the immune response and improves the protective effect of the vaccine.

Probiotics can also help prevent secondary infections. For example, in birds receiving antibiotic therapy, it is quite common for individuals to develop a secondary yeast infection ( Candida Albicans). This is especially true of young or immune compromised individuals.

Yeast, which are a type of microscopic fungi, are normally present in small amounts in our gut and are not affected by antibiotics. When antibiotics are used, most of the bacteria are killed, leaving yeast to take advantage of the newly available space, allowing them to multiply and disrupt the digestive system. Thus, the secondary yeast infection can become just as significant as the primary bacterial infection, and cause the animal to develop additional symptoms.

Giving probiotics during antibiotic therapy restores the bacterial population that is being destroyed, reducing the riskthat a secondary infection will develop. The beneficial bacteria administered via probiotics will mostly be destroyed by the antibiotic but those that survive will help the remaining flora in the gut.

This is why it is important not to give the probiotics at the same time as the antibiotics. It is recommended to separate the administrations of probiotics and antibiotics by at least one hour, with the probiotic ideally given after the antibiotic. This maximizes the number of surviving beneficial bacteria. 

The benefits of using probiotics during periods of stress

Animals, just like humans, experience periods of stress during their lives. During stressful times, our bodies produce cortisol, a hormone that helps us to respond to stress by preparing our body to escape from danger. For example, cortisol increases the heart rate and amount of glucose in our blood so that energy is available for running away, etc. Although this response is useful in the short term, during periods of chronic stress, its effects can be detrimental. One of the negative effects of cortisol is that it suppresses the immune system, leaving us more prone to infection.

In addition to reducing the risk of a secondary infection by improving the bacterial flora, the use of probiotics during periods of stress helps moderate the negative effect stress has on the immune system.

Here are some examples of events which may cause an animal to feel stressed:

  • Moving
  • Arrival of a new pet
  • Loss of a companion
  • New baby
  • A change in the caregiver's schedule
  • A change in the animal's environment
  • Changing an animal's diet
  • Being babysat while the owner is away
  • Boarding elsewhere while the owner is away

In such circumstances, it may be beneficial for the animal to receive probiotics. The probiotic supplementation should start a few days prior to the event and continue through out the stressful period, and for a few weeks after the event has passed.

McEwen BS (2007). "Physiology and neurobiology of stress and adaptation: central role of the brain". Physiol Rev. 87 (3): 873–904. 

Different Types of Probiotics

Many products exist on the market. Each species of animal has a different bacterial flora. Because herbivores eat plants, carnivores eat meat and omnivores eat a little of both, it is no wonder that each has its own unique bacterial flora adapted for digesting these different nutrients. Not only is it useless to give bacteria that is not a normal inhabitant of the animal's gut flora, it can even be detrimental. At best the bacteria arriving in a hostile gut environment will simply not survive, but in some cases these abnormal bacteria can be dangerous. This is because some bacteria that are part of the normal gut flora in some animals are harmful to other species of animals.

For example, bacteria called  Salmonella spp. are part of the normal gut flora in hedgehogs and most reptiles. However, they can be dangerous for many other species, including humans, for whom Salmonella can cause a potentially serious infection of the digestive tract.

Each animal requires a probiotic supplement adapted to its species needs in order to reap its benefits and avoid any negative impact. A supplement tailored to the needs of a particular species will contain only bacteria normally found in that species gut. It is therefore not recommended to give an animal a probiotic formulated for human consumption. It is important to note which types of bacteria are contained in the supplement and to select a probiotic supplement that contains many species of bacteria rather than one containing a single species. This will increase the likelihood that the product will be more effective.

A portion of the ingested bacteria will be destroyed by the gastric acid in the stomach. As such, it is important to select a supplement that has a protective component so that the beneficial bacteria can remain intact until they reach their destination, in the intestine. The survival rate is therefore quite significant, more so than the initial bacterial count.

For certain species of animals, probiotics can come as a capsule or pill. This is one way to protect the contents from being digested by the stomach acid. The protective outer covering is dissolved by gastric acid and the bacteria are released once they reach the intestine. This ensures that the greatest number of bacteria will reach their destination.

For animals unable to swallow a pill due to their size, anatomy or nervous nature,a process called micro-encapsulation offers a solution. The process involves encapsulating the bacteria in a protective layer at the microscopic level. The microscopic encapsulation is just as effective at protecting the bacteria from the acidity of the gastric juices but allows the probiotic to be offered in a powder form. The powder can then be easily administered in food. This means that the amount given can be adjusted for a smaller animal and allows the probiotic to be given with minimal stress since the animal does not need to be restrained.

Not all probiotics are created equal. It is important to be well informed before buying a product.


Sophie Hébert Saulnier graduated from the University of Montreal's faculty of Veterinary Medicine in 2010. During her studies, she completed numerous internships in Quebec and the United-States in order to gain in depth knowledge of exotic animal medicine. For the past 6 years, she has worked exclusively with exotic companion animals and birds in a specialized veterinary hospital. She has given many presentations on the subject of avian medicine to various associations in Quebec, as well as to students in veterinary medicine and animal health sciences. In addition, she teaches at Vanier College's Animal Health department and thus actively contributes to the training of future animal health technicians. In her spare time, she volunteers at a local animal shelter where she gives medical care to abandoned exotic pets, plays in a wind instrument orchestra, practices rock climbing and travels whenever possible. She shares her home with two caïques and two cats.

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