Why your chickens might need essential oils - Interpretive Summary

by Sam Shafer

As producers reduce antibiotic use, scientists examine new strategies to improve bird growth and health

Poultry scientists are investigating new ways to keep birds healthy and shift the poultry industry away from widespread use of antibiotics. Researchers are especially keen to improve antimicrobial strategies for organically raised chickens, which are not given antibiotics.

According to a new paper in Poultry Science^® certain chemicals found in plant-derived essential oils (EOs) may improve meat and egg production while reducing the need for antibiotics. This review, led by scientists in Egypt, the United Arab Emirates and Australia, is based on data from a vast number of studies on essential oils.

The researchers compared studies and found evidence that essential oils from Chile Boldo leaves, fenugreek seeds, dried rosemary, anise seed and cinnamon can improve chicken meat production and quality. They found that oregano, oregano/laurel leaf oil, black cumin seeds, fennel seed oil and sage leaf oil can improve chicken egg production.

Why do these essential oils make such a difference? The researchers found that compounds in EOs help birds maintain a healthy population of gut microbes and a high level of digestive enzymes, which improve nutrient absorption. Birds given EOs can also digest protein better.

EOs can also improve feed taste and smell. Birds simply seem to like them.

Together, these effects lead birds to eat more, gain weight more efficiently and even harbor fewer harmful bacteria in the gut. Overall, EOs appear to boost nutrient absorption.

Many studies also show that EOs perform well in reducing disease and improving bird health. The scientists cite an experiment showing that EOs can prevent and cure necrotic enteritis in poultry. Research also shows that lemongrass oil can inhibit bacterial growth and lemongrass and kaffir lime EOs have antifungal properties.

Meanwhile, EOs from oregano and cinnamon are among those that reduce growth of E. coli and Salmonella bacteria. EOs from oregano reduced parasite infections. And EOs from ginger root and cinnamon improved the antioxidant status of broiler chickens. Garlic appears to be the jack-of-all-trades with significant growth and anti-bacterial effects.

“The dietary supplementation of EOs in poultry may enormously improve their quality of life,” write the study authors.

So how to deliver EOs to flocks? While the compounds in many EOs are notoriously unstable, encapsulating them in ultra-fine particles (a process called nanoemulsion) appears promising. These particles can keep the EO compounds stable, making it easy to add these therapeutic compounds to a flock’s drinking water.

What does this study mean for producers?

Essential oils have been widely studied by poultry scientists and show benefits for fighting disease and improving bird growth and egg production.
EOs can be easily delivered to flocks through drinking water.
EOs don’t come without some risks. Some EOs can irritate the lining of the gut and cause inflammation, so the study authors recommend producers stick to those with proven beneficial effects.

The full paper, titled “Essential oils and their nanoemulsions as green alternatives to antibiotics in poultry nutrition: a comprehensive review,” can be found in Poultry Science^® and online here.

DOI: 10.1016/j.psj.2021.101584