Senior poultry research scientist, Novus, Frances Yan, one of the experts involved in the study, commented: “Coccidiosis is a disease of great economic significance caused by protozoan parasite of the Eimeria genus. The poultry industry takes a prophylactic approach to manage coccidiosis and minimize its consequences by either including anticoccidial drugs or administering vaccines to chicks.”
Essential oils (EO) have been demonstrated to be an effective tool to improve growth performance and gut health of broilers subject to an Eimeria challenge. However, prior to the publication of this research outcome, the concern had been around whether the efficacy of essential oils or vaccines or both is impacted when used in combination.
A study published in Animals in March 2020, also evaluating a thyme/carvacrol EO, suggested that dietary encapsulated essential oils (EEO) could be used as the alternative to anticoccidial agents to mitigate coccidiosis-induced growth depression in broiler chickens.
"Further studies are warranted about whether dietary EEO could counteract environmental stressors such as heat stress or stocking density and improve gut microbiome, antioxidative defense system, and gut barrier functions in broiler chickens," wrote that team.
The trial showed the efficacy of essential oils and coccidiosis vaccines and demonstrated that they can be used together without compromising one another, said Yan.
The essential oil blend used in the study increased body weight prior to the coccidiosis challenge and improved the feed conversion ratio (FCR) throughout, she said. The vaccine did as it is expected – reduced oocyst shedding and improved body weight and feed conversion ratio during the challenge phase, added Yan.
The research was conducted on 576 Ross 308 male broilers; the trial evaluated the efficacy of an essential oil blend (NEXT ENHANCE 150, 1:1 thymol carvacrol) against an Eimeria challenge when it was used alone or combined with a coccidiosis vaccine.
The study consisted of eight treatments in a 2x2x2 factorial arrangement with two levels of vaccination (no or yes), two levels of EOB (0 or 60 g/ton), and two levels of Eimeria challenge (no or yes).
Each treatment had nine replicate pens of eight birds.
Vaccination was administered at the start of the trial with an Eimeria challenge (35X recommended vaccination dose) applied on day 21 via oral gavage, said the team.
Data were subject to 2-way ANOVA before the Eimeria challenge and 3-way ANOVA after the challenge to evaluate the main effects and their interactions.
The study, said the researchers, found supplementation with the essential oil blend increased bird body weights on day 21 and improved FCR on days 13 21, and 29, and that the effect was independent of vaccination or the Eimeria challenge.
Regardless of the essential oil blend use or the challenge, the team said the coccidiosis vaccination had no effect on growth performance on days 13 or 21, but that itimproved body weight and FCR during days 21-29 - the Eimeria challenge phase.
During days 26-28 of the study, the vaccinated birds shed minimal oocysts in excreta and non-vaccinated birds shed a substantial number of oocysts, especially for those challenged with Eimeria, accounting for an interaction between vaccination and challenge, but there was no significant effect of the essential oil product observed for oocyst shedding, reported the team.
The oocyst shedding reduction along with performance improvement demonstrated that the coccidiosis vaccination provided birds with immunity against Eimeria and the protective effect was not impacted by essential oil supplementation, they remarked.
In summary, the research team saw that the essential oil blend increased bird body weight before the Eimeria challenge and improved FCR throughout the trial, while coccidiosis vaccination reduced oocyst output and improved body weight and FCR during the Eimeria challenge phase.
Title: Efficacy of an essential oil blend alone or combined with a coccidiosis vaccine against Eimeria challenge in broilers
Authors: F Yan, J Chen, V Kuttappan, D Hancock, M Vazquez Anon