Chicken Health / Chickens / Fermented Feed / Management

Science of Fermented Feed

Hermann Fuechsel’s “Feeding the Chickens” (1861-1897)

This summer, I started playing with fermented feed after reading a thread about it on the BYC forum.  I wrote a post about my first attempt and the one research article I had read about the benefits, the Enberg1 study, and another post about my second attempt with an improved system.

After a great question from Max, I went to my university’s online database to learn more about fermented feed and its application to poultry.  Most research is tailored for large, corporate “farm”-type operations, but chickens are chickens and we can glean information which does apply to our backyard practices.  My first post, linked above, really covers the basics, and this article covers some additional details.

What is fermented feed?

Fermented feed is any sort of regular chicken feed or scratch which has been fermented with live cultures of bacteria or yeasts.  First, the food is moistened or submersed in water.  Live cultures obtained from natural apple cider vinegar, bread yeast, sourdough starter, brewing yeast, or caught from the air are allowed to begin fermenting the food.  You can use the fermented feed after a few hours although many recommend waiting 24 or 48 hours to get the full benefits.  Some people keep a batch going by taking out the food they need, stirring in fresh, and replenishing the liquid as necessary.  According to some of the research, it is best to allow three days for all fermentation if possible.  The initial stages of fermentation has low levels of the lactic bacteria we want and a high pH.  After a while, lactic bacteria and good yeasts dominate, and the the pH is acidic.5   Of course, there are many factors which would influence how quickly the fermentation goes through those stages, like temperature, amount of inoculant, amount of liquid, nutrient make-up of the feed, and so forth.

Fermented feed is generally fed as a wet mash, having sat covered in liquid and then drained.  In the research, some of the fermented feed was in a liquid state, supposed to be more economical for commercial farming operations.  Other studies used solid-state fermented feed which was made by mixing dry feed with water at a 10:3 ratio, inoculating with cultures, wrapping in plastic, and setting to ferment, reaching ideal levels of fermentation more slowly.5

Alimentary canal of a chicken (McFetridge, 1920)

Why is fermented feed of interest in poultry?

The EU banned “antibiotic growth promoters” prompting commercial growers and the researchers who support the industry to search for alternative ways to maintain their business model without suffering losses or increasing the risk of transferring pathogens like salmonella and campylobacter to consumers.5  Many of us are familiar with salmonella.  Campylobacter is another pathogen that can transfer to humans through contact with chicken meat and is the leading cause of gastroenteritis (stomach flu) in humans.2

What are the effects of wet feed?

Increased nutritional uptake and feed conversion

Interestingly, there are fantastic benefits to just feeding a wet mash, even unfermented.  One of these is greater nutritional uptake, and therefore better feed conversion.   The villi in the intestines1 grow longer and have more surface area which enables them to take up more nutrients.  Because fermented feed is wet, it also increases villi length.  A number of studies have found that wetting the mash increases food uptake, food utilization, weight gain, and egg production.1

A lithograph plate from Gray’s Anatomy. (A) Intestinal villi

What are the effects of fermented feed?

Reduction of pathogenic microorganisms

These studies found that the fermented feed led to a much healthier gastrointestinal tract.  One study suggested that fermented feed should be called “fermbiotics” because it provides the same benefits as probiotics in the human diet.4  Primarily, fermented feed causes a reduction of pathogenic bacteria including salmonella and camphylobactor in the digestive tract, most particularly in the crop and gizzard.  Because the crop often ruptures during slaughter, the decreased level of pathogens in this area in particular makes contamination of the meat less likely.3

Lactic acid is produced by the lactobacteria.  These beneficial bacteria are present in the feces of birds given fermented feed.  This demonstrates that they have traveled throughout the digestive system,  and they may be killing off pathogens along the way.3  The lactic and acetic acid produced by the bacteria in fermented feed create an acidic environment with a pH of about 4.  At this level of acidity, molecules of acid can enter the bacteria through their cell membranes, and the increased acidity within the cells interferes with enzymatic processes, killing the bacteria.3  Fermented feed is somewhat more effective against salmonella than camphylobactor because the lactobacillus also outcompetes the salmonella for nutrients in the feed itself.3  Still, birds fed fermented feed took longer to begin shedding camphylobactor bacteria in their feces after being exposed to the bacteria and were less susceptible than birds on a non-fermented diet.2

Lactobacillus Acidophilus

Increase in egg weight and eggshell thickness

Hens fed fermented feed came to point of lay later, but their eggs were heavier, their feed-to-egg weight ratio was better, and the hens themselves weighed more.1  Egg shell weight, eggshell thickness, and egg weight were all increased.

Nutritional changes in the feed

Soaking and fermenting makes the phosphorus more available to the digestive tract.  Sugar content decreased in the Engberg study by 77% and crude protein increased slightly, by 3%.1    The beneficial bacteria outcompeted moulds in the feed, reducing their prevalence.

A negative is that Engberg found 3% less amino acids in the fermented food because these were consumed by the bacteria, E. coli specifically.  They recommended that inoculating with lactobacillus, such as found in natural apple cider vinegar, would allow the lactobacillus to outcompete the E. coli and leave more of the amino acids intact.


Basically, fermented feed helps birds to gain more weight, lay heavier and stronger eggs, and increase how much production you get out of a bird compared to how much feed you put in.  If you process your chickens, there will be less risk for contamination and the fermented feed might reduce their risk of carrying some harmful bacteria in the first place.  Even if you can’t ferment your feed, you can always get some of these benefits by mixing water into your feed to create a wet mash.

While you’re at it, remember that fermented foods have been a part of the human diet for thousands of years and are the original probiotic supplement.  A little bit of that natural apple cider vinegar with the mother is a great addition to a homemade sports drink: a teaspoon each of ACV, lemon juice, and honey mixed into a glass of water is refreshing after a long day shoveling out the coop!  And pour a bit in your chicken’s waterer while you’re at it!

Charles Angrand’s “Feeding the Chickens” (1884)


1) Engberg, R., Hammershoj, M., Johansen, N., Abousekken, M., Steenfeldt, S., & Jensen, B.  (2009).  Fermented feed for laying hens: Effects on egg production, egg quality, plumage condition and composition and activity of the intestinal microflora.  British Poultry Science. doi: 10.1080/00071660902736722

2) Heres, L., Engel, B., Van Knapen, F., Wagenaar, J., & Urlings, B.  (2002). Effect of fermented feed on the susceptibility for Campylobacter jejuni colonisation in broiler chickens with and without concurrent inoculation of Salmonella enteritidis.  International Journal of Food Microbiology, 87, 75-86.

3) Heres, L., Wagenaar, J. A., Van Knapen, F., & Urlings, B. (2003).  Passage of Salmonella through the crop and gizzard of broiler chickens fed with fermented liquid feed.  Avian Pathology, 32, 173-181.

4) Niba, A., Beal, J., Kudi, A., & Brooks, P. (2009).  Bacterial fermentation in the gastrointestinal tract of non-ruminants: Influence of fermented feeds and fermentable carbohydrates.  Tropical Animal Health and Production, 1393-1407. doi: 10.1007/s11250-009-9327-6

5) Yu, Z., Dong, B., & Lu, W.  (2009). Dynamics of bacterial community in solid-state fermented feed revealed by 16S rRNA. The Society for Applied Microbiology: Letters in Applied Microbiology, 49, 166-172.

Other articles:

Chen, K., Kho, W., You, S., Yeh, R., Tang, S., & Hsieh, C. (2009). Effects of Bacillus subtilis var. natto and Saccharomyces cerevisiae mixed fermented feed on the enhanced growth performance of broilers. Poultry Science, 88, 309-315.

Heres, L., Engle, B., Urlings, H., Wagenaar, J., & Van Knapen, F.  (2004).  Effect of acidified feed on the susceptibility of broiler chickens to intestinal infection by Campylobacter and SalmonellaVeterinary Medicine, 99, 259-267.

Heres, L., Urlings, H., Wagenaar, J., & de Jong, M. (2003). Transmission of Salmonella between broiler chickens fed with fermented liquid feed.  Epidemiology and Infection, 132, 107-116. doi: 10.1017/S0950268803001213

Fermented Feed Posts:

#1: Fermented Feed

#2: Fermented Feed v2

#3: Science of Fermented Feed

#4: Microorganisms at Work

#5: 10 Foods to Ferment for Chickens


Shared with Farm Girl Friday

18 thoughts on “Science of Fermented Feed

  1. My chickens love the fermented feed. They come running from across the yard when they see the bucket. I just started a small batch for the new born chicks. Thanks for sharing this info a few months back.

    • Mine love it, too! I haven’t been feeding it regularly since the school year started, but I have been giving them big bins of fermented grower feed and mashed hard-boiled eggs to help them through the molt. There is never a single speck of it left!

  2. Made a batch of rose hip & bilberry wine – will the mash be good for the chickens and should i mix with something as it seems strong.

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  11. We are currently using grain mill egg layer crumbles. Can this be fermented ? Do you have your own custom mix that you would share the proportions with us? My husband has been fussing about how much feed we are using, but I hate to cut back when it is below zero outside and they won’t go outside and cant forage anyway…….Thanks for this article and any advice you can give us. We currently have 28 dual perpouse rare breeds and 2 roosters…….. Evie

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