Probiotics For Chickens: What They Do & When To Use Them

What Are Probiotics 

Probiotics are foods or dietary supplements that contain live bacteria. They are given to animals (and people too) in order to add to, or replace, the bacteria that exists in the animals gastrointestinal tract.  Probiotics are said to provide health benefits but these benefits are generally not well explained or understood.

So Whats Going On in the Gut

Animal gastrointestinal tracts are populated by hundreds of different species of bacteria in mind-boggling numbers (There are billions and billions of bacteria in any animals gut). 

A chickens gut harbors billions of bacteria

Each of these types of bacteria competes for food and living space until all the available food and living space in the gut are used up. The type of bacteria and the numbers of each type of bacteria varies from individual to individual and changes over time as the animal is exposed to new types of bacteria. 

Most of the bacteria in an animals gut are not harmful. However, even seemingly healthy animals will have a some harmful bacteria such as e-coli, or salmonella in their guts. However, the bad bacteria are in such small quantities that they can't do any harm.  The population of these bad bacteria are held in check by the good bacteria that out-compete them for resources and keep their numbers so low they can't make the animal sick.

When It Makes Sense To Use Probiotics

A healthy adult chicken will already have a gut composed primarily of good bacteria. If you give that chicken a probiotic that contains new strains of good bacteria, you might alter the population balance between various good bacteria strains in its gut, but not necessarily improve the chickens health. Basically, you would be just swapping in a new good bacteria for an old good bacteria or increasing the level of one kind of good bacteria relative to other good bacteria in the chickens gut. Therefore, we don't see much benefit in providing probiotics to healthy adult chickens. However, the key words here are "healthy" and "adult." 

Healthy adult chickens don't need a probiotic supplement

Newborn chicks don't have guts that have had time to build up strong populations of good bacteria. Newborn chicks are more susceptible to having bad bacteria out-compete good bacteria if they are exposed to a potent source of bad bacteria. Contaminated food or water dishes are one possible source of bad bacteria. Chick feed may also harbor bad bacteria if it has been contaminated by rodent droppings.

We recommend providing a probiotic to chicks for the first week of life. This seems like a reasonable and cheap pre-caution.

We recommend giving newborn chicks a probiotic

We also think it makes sense to provide probiotics to adult chickens in certain circumstances. As mentioned earlier, a healthy adult will already have established its gut bacteria. Backyard chickens in particular get plenty of exposure to healthy bacteria by snacking on yard plants and bugs, treats and table scraps.

However, chickens suffering from a particular bacterial disease may be treated with antibiotics. The antibiotic will kill off the bacteria and it would also destroy beneficial bacteria in the chickens gut. This would leave the door open to bad bacteria to take over the niche formally held non-harmful strains or bacteria.


Providing probiotics to adult chickens after they have been treated with antibiotics also seems like a reasonable course of action. By "after" we mean giving your chickens probiotics for a week or two after they have taken the last dose of antibiotics. Why? Because antibiotics will also kill the good bacteria in the probiotic so provide the probiotics immediately after the last dose of antibiotics . 

Sources of Probiotics
Chicken owners can buy probiotics online and at feed stores. Most of these concoctions contain a relatively small variety of good bacteria including the following strains:

• Lactobacillus acidophilus
• Lactobacillus casei
• Lactobacillus bulgaricus 
• Lactobacillus plantarum
• Streptococcus thermophilus
• Enterococcus faecium
• Bifidobacterium

Another approach is to feed your chickens a small amount of food that contains these same good bacteria. The advantage of this approach is that foods will contain many more beneficial strains of bacteria than the commercial products and you may already have them in your refrigerator so they cost you nothing. 


NOTE ON DAIRY PRODUCTS: Chickens have a difficult time digesting dairy products. If you provide cheese or yogurt do so in small quantities and only to adult chickens (not chicks). The best yogurt will contain little or no sugar. Try to get relatively unprocessed brands such as Chobani, Fage, La Yogurt, and Dannon. The same applies to cheese; relatively unprocessed soft cheeses are best. Raw milk "artisanal" cheese is the best.

Natural sources of these probiotics include yogurt, sauerkraut, sourdough, miso, and soft cheeses.

Probiotic Strains Typically Found in Yogurt

• Lactobacillus acidophilus
• Lactobacillus casei
• Lactobacillus bulgaricus
• Streptococcus thermophilus

Probiotic Strains Typically Found in Sauerkraut

• Lactobacillus plantarum

Probiotic Strains Typically Found in Sourdough Bread

• Lactobacillus plantarum

Probiotic Strains Typically Found in Miso (Japanese Soup)

• Aspergillus oryzae (a fungus)

Probiotic Strains Typically Found in Soft Cheese (Gouda, Mozzerella, Colby)

• Bifidobacterium
• Enterococcus faecium
• Lactobacillus acidophilus
• Lactobacillus casei

What about Apple Cider Vinegar (ACV)?

Many chicken owners give their chickens apple cider vinegar because they believe it provides health benefits to their chickens.  However, Acetobacter is not a probiotic. It differs in a very important respect from every other strain of bacteria mentioned so far in this article. Acetobacter requires oxygen to live and there is no oxygen in the gut. Acetobacter can't survive in the gut and so it can't out-compete the bad bacteria.

ACV alters the pH in the gut to make it more acidic. Commercial poultry operations acidify their chickens water in the week prior to slaughter, but they do this to decrease the overall level of bacteria (bad and good) in the gut so as to limit contamination during processing.