Advances in feed additives are transforming coccidiosis management beyond traditional anticoccidial drugs. Research highlights the promise of essential oils, plant compounds, and microbial products in supporting gut health and boosting broiler performance.
Coccidiosis, which is caused by the massive proliferation of the Eimeria organism within intestinal epithelial cells, remains a common poultry disease that causes widespread economic losses. The replication of this parasite causes huge damage to the intestinal mucosa. This, of course, negatively impacts nutrient digestion and absorption, reducing chicken growth rate and affecting overall broiler health.
Current strategies: Anticoccidials and vaccines
While current control strategies focus on the use of anticoccidial drugs and live vaccines, often in rotation or in various combinations, there are concerns that the coccidiosis parasite may develop drug resistance. There are also worries about drug residue accumulation. There is thus great interest in natural substitutes.
Exploring plant-based feed additives
Plant extracts and compounds have been explored for their anticoccidial potential, and there is strong evidence of their effectiveness. These include extracts from Meliae toosendan (the dried fruit of a deciduous tree) that contain over 190 compounds with pharmacological activity. Maslinic acid is another plant biochemical that stands out: a compound from the olive tree with anti-cancer, anti-inflammatory, and other properties. However, combinations of plant compounds have been shown to be more effective than single products in some cases.
Essential oils in feed: Recent research highlights
Indeed, a blend of essential olive oils for treating coccidiosis is the subject of a recent study published by Dr Junlong Zhao of the National Key Laboratory of Agricultural Microbiology at Huazhong Agricultural University in China, and Dr Gaiqin Wang of that Laboratory and of Anyou Biological Technology Group.
Zhao and Wang explain that plant essential oils enhance poultry production performance by improving nutrient digestion and absorption, as well as by enhancing antioxidant status and immune responses. Essential oils commonly used in broiler diets worldwide include anise, oregano, cinnamon, garlic, thyme, and turmeric. Specifically, Zhao and Wang note that the inclusion of oregano essential oil, fennel essential oil, or a blend of thyme, mint and eucalyptus essential oils in the chicken diet has been shown to increase intestinal villus height and width and reduce crypt depth.
Optimal supplementation and challenges in trials
From their results, they conclude that an essential oil blend (200 g/t and 400 g/t, with g/t being grams/tonne) can serve as a feasible adjunctive alternative to traditional anticoccidial regimens for broilers under a high-dose coccidial vaccine challenge stress (trivalent live coccidiosis vaccine containing Eimeria tenella, Eimeria maxima and Eimeria acervulina). The active components in their essential oil blend were 3% cinnamaldehyde, 1.8% carvacrol, 2% thymol and 10% gallnut, in a carrier of silicon dioxide.
They concluded in their study that 200 g/t “was the optimal supplementation level, exerting the most significant effects on improving intestinal mucosal health, regulating immune function and alleviating coccidial vaccine-induced damage.” However, they note that the immune response and lesion characteristics induced by a high dose of coccidial vaccine differ from those induced by wild-type virulent strains of coccidiosis, and the use of a high dose of coccidial vaccine for challenge in this study therefore has limitations.
Feed interventions and gut health: The broader perspective
Cargill Director of Strategy & Innovation Dr Manuel Da Costa (PhD, veterinarian) and his colleagues recently presented a Poultry Science Association abstract that examines the broader picture of how coccidiosis control programmes, diet, and feed additives affect gut health. In their study, they looked at three control programmes under a mild enterococcus challenge, and how they might abet the proliferation of pathogens. The three programmes consisted of a chemical treatment (zoalene), an Ionophore (narasin) and a coccidiosis live vaccine. “In addition, we layered on top a postbiotic-essential oil combination product to understand its effects,” says Da Costa. “What we have learned is that overall, this product combination did ameliorate performance across the board.” The team notes that these different coccidiosis-control methods impact the gut ecosystem differently (affecting the presence of enterococcus), ‘setting the stage’ for either a balanced or unbalanced microbiome, and influencing the succession of gut microbes as a chicken grows.
Integrated feed strategies for microbiome balance
Overall, they believe the best strategy to ensure a balanced, healthy microbiome is to achieve steady, early establishment of beneficial bacteria. And the way to achieve this is to pair anticoccidial strategies with tools such as plant compounds and/or microbial feed additives.
“As more complex problems arise and as industry navigates towards precision production, we should see things as systems. Things are integrated, and therefore we should evaluate and address them as such.” – Dr Manuel Da Costa, Cargill.
Beyond silos: Precision feeding for poultry health
When asked about the overall potential of microbial ‘postbiotic’ feed additives, plant compounds and other tools in the context of coccidiosis control and gut health, Da Costa first notes that the industry tends to view poultry health problems in silos and address them as isolated issues. “For some things, this works because we have targeted tools that have worked in addressing them,” he says. “However, as more complex problems arise and as industry navigates towards precision production, we should see things as systems. Things are integrated, and therefore we should evaluate and address them as such.”
That is, as precision production draws closer, Da Costa advises that as we become more specific in our disease interventions, we must carefully examine the details and avoid a one-size-fits-all approach. A product can work very well in one circumstance but perform poorly in others. To address this, he says, “we should capture data and leverage microbiome analysis to understand the true effects of the product.”
Evaluating feed additives and combinations
In addition to the fact that some microbial and plant-based products work in some instances but less effectively in others, Da Costa notes that we also tend to speak of these products as catch-all categories. “However, within them there different products with different merits,” he says. “For example, postbiotics are not all the same.” He notes that Cargill manipulates the fermentation process to obtain different metabolites, which affects how those products should be used. “It’s the same with phytogenic components, essential oils, etc.,” he notes.
And while components are already on the market, others remain to be discovered. In Da Costa’s view, both groups of products should be examined in terms of how they work in isolation and how they can be combined to unlock the best synergies. He stresses that this approach must be science-backed and supported by strong evidence, both from the ‘live’ side performance and also from a ‘mechanism of action’ standpoint.
Adoption challenges for feed solutions
Given how widely these products are already used, Da Costa notes that in the USA, plant-based and microbial tools are increasingly adopted, but each customer has a different view. “Reasons for low adoption are added cost with no perceived benefit for their key performance indicators, consistency of results and true understanding on how these products work,” he says. “I believe the fact that there is a lot on offer in terms of variety and quality might be affecting [the obtainment of] a clear understanding of the value of these products.”
