Around the world there are increasing concerns over antibiotic resistant strains of bacteria and the generation of super-bugs resulting from the overuse of antibiotics both medically for people and in the production of livestock. The mathematics of the situation for livestock are pretty simple. The more animals you crowd into close quarters, under stress, and kept on minimized inputs for maximized profits, the more likely you are to face disease and health issues with the animals.

That’s why a lot of people, myself included, turn to keeping their own chickens as a way to ensure high quality eggs and/or meat, and better well being for the livestock involved. But small scale production does not eliminate the inherent risks of raising poultry, which include exposure to pathogens like E. coli, Salmonella and Listeria to name only a few.

Wouldn’t it be great if there was a natural way to handle these potentially deadly pathogens?

Turns out researchers have been asking that question too. Studies have been focusing on using plant-based essential oils in the production of chickens. The goal is to determine if these compounds can work effectively to improve productivity while eliminating the risk of developing chemical resistance.

My curiosity was peaked because I have read a little about using herbs and essential oils for chickens, but always thought it was really just about making the coop smell fresher. As I have dived into the research, I now realize that essential oils may be an indispensable tool for small scale farmers to improve their flocks and increase the quality of their meat and eggs.

If you have ever wondered about whether essential oils are really worth the hype then keep reading! I have pulled together some of the latest research findings that may help shed some light on this intriguing approach to chicken management.

What is an essential oil?

Essential oils are fragrant compounds derived from plants through extraction methods like fermentation, expression or steam distillation (1). Oils may be created from various plant parts such as flowers, fruits, seeds, leaves, bark, roots or from the entire plant.

Each oil has characteristic odors and biological activity that relate to the parent plant from which it is derived. Therefore, the quality of the oil depends on how the plant was grown, which part was harvested, and the extraction process used.

Typically, essential oils are highly concentrated and must be diluted with carrier oils or organic solvents before use. They should never be applied full strength directly to humans or livestock of any kind. The dilution rate will affect the types of biological activity the oil displays.

100% pure Eucalyptus

Always be sure to follow recommended dosages from experienced practitioners, or start out slowly if you are experimenting with essential oils on your own. If there is any doubt, then consult with a veterinary or animal health professional . The information in this post is intended to inform you about the latest science on essential oils, and it’s not meant to diagnose or treat chickens, livestock or people.

Always remember with essential oils, that a little oil goes a long way. That means that adding more essential oils or increasing the concentration of the final solution may NOT result in better performance or health for your birds.

This is particularly true when essential oils are used as feed additives. While small amounts may enhance digestion and improve feed conversion rates for weight gain, excessive amounts may irritate sensitive mucous membranes of the birds, especially chicks, and can lead to the opposite result (i.e. decreased feed consumption and utilization) (3).

A Little Goes A Long Way – Dilution Rates of Essential Oils

Never apply undiluted essential oils to a chicken or a surface that the bird will be in direct contact with. Essential oils should always be diluted for maximum efficiency and effectiveness. As a basic rule of thumb, the essential oil should be between 0.5 and 2% of the final mixture, although dilutions as low as 0.02% may still show biological activity in some of the oils (2).

Typically the essential oil is blended with a small amount of neutral carrier oil, such as olive oil, sunflower oil or canola oil, and then further diluted with water or other liquids to vastly reduce the concentration of the essential oil.

According to Christine Rice, of mountainroseherbs.com:

Whichever dilution method you choose, the essential oil content should only account for 0.5% to 2% of the total blend. This equates to 3 to 12 drops per ounce [30 ml] of finished product.

The most critical take home message here is that essential oils work best in tiny quantities. TINY quantities. What that means is first you create a dilution of the essential oil with a carrier oil, and then you further use that dilution in drinking water or feed. It ends up being only a few drops of diluted essential oil in a gallon of water. As previously mentioned, increasing the concentrations of the oils in the solution may do more harm than good.

If you are new to using essential oils or are introducing them to your flock for the first time, start out low and slow. Essential oils are too powerful to use directly. Christine has made a great dilution chart that is easy to use for figuring out how much of the carrier oil and essential oil you need to mix to make a 1% or 2% product. If you are blending several essential oils together, remember to keep to the total concentration of aromatic oils to 2% or less of the final product. And from that dilution, you further reduce the concentration by mixing drops into water or feed. It is a very tiny amount.

The Biological Activity of Essential Oils

Quality essential oils are reactive in the body and perform as well or better than many antibiotics and drugs when applied to chicken production (1). That is why the poultry industry has been looking into using essential oils in place of other chemical interventions which often have serious side-effects, such as the development of antibiotic-resistant bacteria strains.

Disease organisms, yeasts, fungi, bacteria and parasites are unlikely to develop resistance to the plant-based essential oils (2). Because these compounds are considered safe and natural, there is no withdrawal period for their use in poultry (2). However, some essential oils (most notably those of garlic and onions) will affect the flavor of the meat and eggs and may require a resting period if those flavors are considered undesirable.

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How are essential oils used for chickens?

Essential oils can be used to specifically target pathogens such as bacteria, viruses, and parasites in poultry. This is amazing news for the small-scale producer!

In fact, essential oils can be used effectively against some of the most villainous characters in chicken production, like E. coli, Listeria, Salmonella , Streptococcus and Coccidiosis (caused by any one of seven pathogenic Eimeria species).

100% pure Oregano oil

The chart below has a visual representation of which essential oils are biologically active against which chicken villains, based off the tables in the 2017 review paper (2).

Unlike medications or antibiotics, essential oils can be used to fight against molds, fungus, bacteria and viruses without requiring a withdrawal period prior to use of the meat or eggs (2, 3).

Twelve Main Poultry Pathogens Treatable With Essential Oils

Micro-organism/Pathogen	Essential Oils
Aspergillus niger	Eucalyptus; Oregano
Bacillus cereus	Rosemary; Sage
Bacillus subtilis	Oregano; Rosemary; Sage; Thyme
Candida albicans (yeast)	Eucalyptus; Garlic; Oregano; Thyme
Eimeria	Oregano; Thyme
Enterobacter cloacae	Oregano; Peppermint; Rosemary; Thyme
Enterobacter faecalis	Thyme
E. coli	Eucalyptus; Garlic; Oregano; Peppermint; Sage; Tea Tree; Thyme
Listeria monocytogenes	Oregano; Peppermint; Rosemary; Sage; Thyme
Pseudomonas aeruginosa	Peppermint; Thyme
Salmonella sp.	Eucalyptus; Garlic; Oregano; Peppermint; Rosemary; Sage; Tea Tree; Thyme
Staphylococcus aureus	Eucalyptus; Garlic; Oregano; Peppermint; Rosemary; Sage; Tea Tree; Thyme

You can also download the following color chart:

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And The Science Says . . .

Essential oils for chickens are not simply about making your coop smell fresh or providing some relaxing aromatherapy for your laying hens. These oils have been shown experimentally to deliver improved flock performance, productivity and health.

A 2013 controlled study showed that a combination of essential oils (which included eucalyptus, thyme and lemon) administered in drinking water at a rate of 0.05% essential oils significantly reduced Salmonella contamination of the birds’ crops. This resulted in less cross-contamination during the slaughter and butchering processes as well.

A 2014 study showed that the addition of 0.5 g of thyme essential oil per kg of feed significantly boosted immunoglobulin A (IgA) in poultry. IgA is an important immune system molecule that helps ward off sickness. Thus thyme helps to boost the chicken’s immune system and reduce the effects of exposure to pathogens.

100% pure White Thyme

A 2018 review of essential oil use in poultry reported that supplementing thyme essential oil in the diet reduces the oxidation of fatty acids in chicken meat and eggs, leading to longer shelf-life. Thyme, oregano, rosemary and sage essential oils all show this antioxidant effect when used in poultry diets, either as feed or drinking water additives. To state that more clearly: that means by feeding the thyme oil to the chickens in the diet or water, the resultant poultry products have a longer shelf life.

The same 2018 review also noted multiple studies which showed improved weight gain and feed conversion ratios when essential oils were included in broiler diets (3). The mechanism for this change is thought to involve improvements in digestive enzyme activity and stabilization of the gut microflora.

Essential oils, notably thyme and peppermint, but also others like eucalyptus, tea tree and citrus, are used for disinfecting poultry houses and equipment. These oils help to improve the quality of meat and eggs products by minimizing contamination with pathogens (2, 3).

A 2019 study using a blend of oregano essential oil and thyme oil showed that broilers significantly increased their weight by day 28 of the study compared to the control group, with the final weights being 4.5% higher in the treated birds. This study showed a significant change in the intestinal microorganisms, and a further 2020 follow up study showed significant changes in the cecal microorganisms. These changes affect the way chickens digest food and lead to improvements in growth.

What does this mean for a small scale chicken farmer?

These studies are mostly focused on industrial chicken production. That means the environment and diets of the subject chickens are usually highly controlled. Those factors are unlikely to happen on a small scale farm. Therefore, these results with essential oils need to be considered carefully as to what makes sense for a small farm where chickens typically have better and more spacious living environments, and eat a more varied diet.

My take-home thoughts from this research are that essential oils are worth investigated further for small farms. If you have the ability to divide up your birds and treat only some of them with essential oils while keeping all the other food, water and housing conditions the same, then you can learn first hand what works best for your breed and existing flock management. But use caution! The concentrated nature of essential oils means you need very little to have a positive effect and too much will result in a negative effect.

Essential Oils vs Herbs

While many of the plants from which essential oils are derived are easy to grow – such as the culinary herbs oregano, rosemary, sage and thyme – the challenge can be in growing enough to use fresh, and also to dry and store for later use, while at the same time not obliterating your herb garden.

That being said, I grow and use fresh culinary herbs for my chickens and from time to time I give them some. I simply use patches of herbs as part of my landscaping so that they can grow in abundance. I snip off some oregano or other herbs I have growing and toss them to the chicken pens at feeding time. I rarely find any left later, suggesting that the chickens enjoy the “herbilicous” snack. I consider it a free-choice, self-medication option: they can choose to eat the herbs or not. Any herbs that are left just get swept up with the litter and composted. If you are going to feed herbs to your chickens, always make sure you are working with safe herbs.

The thing is that herbs don’t grow in most places in the winter. But, the highly concentrated nature of essential oils can make them a cost-effective alternative for any small farm interested in using botanical, natural supplements in their poultry production. They are ready on the shelf at any time of year. Therefore if you notice a bird that is under the weather, or your flock seems to be under performing, it’s easy to reach for some essential oils and mix up a tonic. And that is rather the point, it is unlikely that a healthy small farm flock needs to be “treated” with herbs, essential oils or medications all the time. It is good, however, to have a back up plan!

Remember that the quality of the essential oil depends on how well the plant was grown and treated. I look for quality brand names that offer information such as organic production, standardization, independent certification, and 100% pure on the labels. Essential oils should be stored in dark glass bottles at room temperature, away from sunlight.

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The Sweet Smell of Success

Essential oils offer an interesting alternative to the use of antibiotics and harsh chemicals in the production of meat and eggs. All the papers I have read call for more research into the factors that enhance the success rate of essential oils and that determine appropriate dose rates for application.

All too often, small scale producers are shut out of industry advancements due to the cost of implementing changes. However, essential oils are within the reach of any scale of chicken production and hold out the hope of improved animal care simultaneously with improved productivity. It’s a win for chickens and farmers alike.

If you are ready to crack open a bottle of aromatic essential oil and get started, remember to evaluate your situation carefully, start low and slow, and consult with a professional or veterinary if you have any questions or concerns.

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