Non-Conventional Strategies to Combat Coccidiosis in Poultry: Herbal Extracts & Feed Additives

Introduction

Poultry production faces a significant challenge in the form of coccidiosis, a widespread enteric parasitic ailment caused by protozoan parasites of the genus Eimeria (Santos et al., 2014; Acharya & Acharya, 2017; El-Ghany, 2021; Alsayeqh & Abbas, 2023; Mathis et al., 2024). These parasites infect the intestinal epithelium of chickens, leading to intestinal damage and substantial economic losses due to poor feed conversion, reduced growth rates, and increased mortality (Adjei-Mensah & Atuahene, 2023; Sharma & Kim, 2024). For many years, the poultry industry has relied heavily on anticoccidial drugs to prevent and control this disease (Acharya & Acharya, 2017; Sharma & Kim, 2024). However, the continuous and extensive use of these drugs has led to the mounting problem of drug-resistant Eimeria strains, raising concerns about their long-term efficacy (Ahmad et al., 2024; Madlala et al., 2021). This resistance, coupled with increasing consumer awareness and governmental pressure for natural food production, is driving a shift away from traditional chemotherapy (Alsayeqh & Abbas, 2023; Sharma & Kim, 2024). Consequently, nutritional interventions and the use of feed additives are becoming increasingly important as effective and sustainable strategies to combat coccidiosis (Madlala et al., 2021; Sharma & Kim, 2024). As consumers increasingly choose organic and chemical-free poultry products, the manipulation of nutrition and the inclusion of natural feed additives offer promising avenues to maintain bird health and productivity without the drawbacks of conventional anticoccidials (Acharya & Acharya, 2017; Ahmad et al., 2024). Therefore, there is a need for a comprehensive exploration of the role of specific nutrients, dietary strategies, and feed additives in modulating the gut health, immune response, and overall resilience of poultry against Eimeria infection (Adedokun & Olojede, 2019). By understanding these interactions, scientists and farmers can work together to develop more efficient nutritional strategies to mitigate the detrimental effects of coccidiosis and ensure sustainable poultry production.

Coccidiosis in Chicken: Nutritional Perspective

Coccidiosis in chickens, caused by the intracellular parasitic protozoan of the genus Eimeria (Acharya & Acharya, 2017; Alsayeqh & Abbas, 2023), significantly disrupts the gut environment, leading to impaired digestion and reduced growth performance (Santos et al., 2014; Madlala et al., 2021). Upon infection, Eimeria species reside in the chicken intestinal epithelium, where they multiply and cause substantial destruction of intestinal cells (Alsayeqh & Abbas, 2023). This damage to the mucosal barrier and underlying tissue results in lesion formation, inflammation, and necrosis in a site-specific manner (R. Tonda et al., 2024). Consequently, the integrity of the intestinal epithelium is compromised, leading to increased intestinal permeability and allowing essential nutrients and proteins to seep out (Ahmad et al., 2024). This malabsorption and enteritis directly contribute to both the subclinical and clinical symptoms of coccidiosis (Ahmad et al., 2024; Santos et al., 2014).

The pathogenesis of coccidiosis severely affects the digestion and absorption of vital nutrients. The destruction of host mucosal cells and the associated inflammation lead to a decrease in digestive enzyme activity and nutrient transporter expression, thereby impairing the digestion of carbohydrates, proteins, and fats (Chalvon-Demersay et al., 2021; Myers & Rochell, 2024). Studies have shown that coccidiosis can decrease the digestibility of nearly all amino acids and lower their plasma concentration (Chalvon-Demersay et al., 2021). Furthermore, the infection can disrupt the absorption of minerals and fat-soluble vitamins (Kiarie et al., 2019; Oikeh, 2019). For instance, calcium absorption is impaired during coccidial infections (Kiarie et al., 2019; R. Tonda et al., 2024). The leakage of proteins and other nutrients into the intestinal lumen further exacerbates the issue, reducing the overall efficiency of nutrient utilization (Ahmad et al., 2024).

Coccidiosis also induces significant modifications in the gut morphology and microbiota. The infection is associated with decreased villus height and number of goblet cells, affecting the absorptive surface area of the intestine (Chalvon-Demersay et al., 2021). Disruption of the gut environment due to Eimeria infection causes an imbalance in intestinal homeostasis, driving the increment of pathogens such as Clostridium species (Madlala et al., 2021). The damage to the intestinal epithelium can also promote mucogenesis, which can further support the growth of certain pathogenic bacteria (Jespersen, 2023). These alterations in the gut microbiota can compound the negative effects of coccidiosis on digestion and overall gut health (Madlala et al., 2021).

Ultimately, the cumulative effects of intestinal damage, nutrient malabsorption, and gut microbiota imbalance due to coccidiosis lead to poor feed conversion ratios and reduced growth rates in poultry (Alsayeqh & Abbas, 2023). Even subclinical infections, without obvious clinical signs, can significantly impact productivity and feed efficiency due to compromised nutrient absorption and utilization (Acharya & Acharya, 2017; Sharma & Kim, 2024). Understanding how coccidiosis pathogenesis disrupts the gut, digestion, and growth performance is crucial for developing effective nutritional strategies to mitigate these detrimental effects and maintain optimal poultry production.

Nutritional and Organic Approach to Combat Coccidiosis in Chickens

1. Herbal Extracts

The increasing prevalence of resistance to standard anticoccidial drugs in poultry production highlights the urgent need for effective alternative nutritional strategies (Madlala et al., 2021; Sharma & Kim, 2024). Resistance has been well-documented against a wide array of anticoccidials, including synthetic chemicals like halofuginone, clopidol, decoquinate, and amprolium, as well as ionophores such as monensin, lasalocid, narasin, and salinomycin (Acharya & Acharya, 2017; Sharma & Kim, 2024). This widespread resistance compromises disease management and necessitates the exploration of natural alternatives, particularly herbal extracts, which have garnered considerable attention for their anticoccidial potential (Madlala et al., 2021; Ahmad et al., 2024).

Garlic (Allium sativum) is frequently used in poultry diets, often as garlic powder or allicin-rich extracts (Madlala et al., 2021; Siddiqa et al., 2024). The active compounds, notably allicin and other organosulfur compounds are thought to exert anticoccidial effects by disrupting the parasite's cellular processes and reducing oocyst shedding (Alsayeqh & Abbas, 2023; Ahmad et al., 2024). Madlala et al. (2021) supplemented the feed of broiler chickens with garlic powder at 2%, concluding that it had antioxidant and anticoccidial effects in Eimeria-infected birds (Madlala et al., 2021). In another study, Adjei-Mensah and Atuahene (2022) included an allicin-rich extract at 0.2% in the diet of layer chicks from day 1 to week 8, observing positive responses (Adjei-Mensah & Atuahene, 2023).

Artemisia annua (Sweet Wormwood) extracts, often processed into granulated formulations, contain the active compound artemisinin, known for its antiprotozoal properties (Acharya & Acharya, 2017; Ahmad et al., 2024). These extracts are believed to interfere with Eimeria species' growth and proliferation within the chicken's gut, reducing oocyst output (Ahmad et al., 2024). Studies have demonstrated that granulated Artemisia extract administered at 1 g/kg of feed to broiler chickens from day 1 to 42 days showed prophylactic and therapeutic effects against coccidiosis (Acharya & Acharya, 2017). In a study where broiler chickens (21 days old) were fed on diets containing 0.5% Artemisia annua leaves, alterations in digesta pH and muscle lipid oxidation products were found (Biagini et al., 2022).

Tannic acid extracts, typically derived from sources like Rhus chinensis gallnuts, contain tannins as the primary active compounds (Tonda et al., 2024). These compounds may exhibit anticoccidial activity through direct effects on the parasite or by modulating the host's immune response and gut environment (Tonda et al., 2024). A study also evaluated a tannic acid extract (TAE) at 0.5 g/kg in the feed of male Cobb × Cobb 500 broilers from day 0 to 20. In the study they reported a reduction in faecal oocyst counts in birds challenged with Eimeria at day 14 (R. M. Tonda et al., 2018).

Curcumin, the main active compound in turmeric (Curcuma longa), is explored as a feed additive, either as ground turmeric or extracted curcuminoids. Its mechanism of action involves anti-inflammatory and antioxidant properties, which can help mitigate the damage caused by Eimeria infection (Sharma & Kim, 2024). A study examined the effects of curcumin compounds at doses of 200, 400, and 600 mg/kg of feed in broiler chickens challenged with Eimeria and observed improvements in growth performance and antioxidant status (Biagini et al., 2022).

Essential oils, such as those containing thymol, carvacrol, and cinnamaldehyde, are volatile compounds with demonstrated antimicrobial and anticoccidial properties (Biagini et al., 2022; Alsayeqh & Abbas, 2023; Ahmad et al., 2024). Alsayeqh et al. (2023) demonstrated the in vitro destruction of Eimeria oocysts by essential oils (Alsayeqh & Abbas, 2023). Biagini et al. (2022) investigated a combination of herbal components, including carvacrol, thymol, and cinnamaldehyde, in broiler chicken feed at 0.025% and reported impacts on coccidia control and performance (Biagini et al., 2022). Another study assessed a blend of benzoic acid and essential oil compounds, including thymol and carvacrol, at 1 kg/ton in broiler diets as an alternative to antibiotic growth promoters, noting positive effects on performance (Santos et al., 2023).

While these herbal extracts exhibit promising anticoccidial activities, their efficacy can be influenced by various factors, including the quality of the extract, the concentration of active compounds, the specific Eimeria species involved, the age and health status of the birds, and the overall farm management practices. Further research is crucial to standardize the use of these natural alternatives and to optimize their application in practical poultry production (Madlala et al., 2021; Biagini et al., 2022; Sharma & Kim, 2024).

2. Feed Additives

In seeking nutritional alternatives to standard chemotherapy for coccidiosis in poultry, various feed additives have demonstrated promising potential for both prevention and support during treatment.

Organic acids are one such category, acting primarily through their antimicrobial properties within the gut. Acetic acid, for instance, has been shown to mitigate the negative impacts of Eimeria tenella infection in broiler chickens when supplemented at 3% in the diet, likely by reducing caecal pH. Anticoccidial effects were observed with dietary butyric acid supplementation in broiler chickens, with evidence suggesting it enhances intestinal barrier function (Kiarie et al., 2019; Alsayeqh & Abbas, 2023).
Probiotics, which are live beneficial microorganisms, are another area of focus. While specific anticoccidial mechanisms may vary, their general mode of action involves modulating the gut microbiota and enhancing the host's immune response. Madlala et al. (2021) conducted a study and found that certain probiotics could offer comparable performance and coccidiosis control. Specific dosages and strains would determine the efficacy (Madlala et al., 2021).
Prebiotics, non-digestible feed ingredients that promote the growth of beneficial bacteria, can also play a supportive role. Mannan-oligosaccharides (MOS) had an anticoccidial effect against experimentally induced coccidiosis in broiler chickens (Alsayeqh & Abbas, 2023).
Minerals also contribute to the bird's ability to withstand coccidial challenges. Zinc, particularly organic forms, has been investigated for its role in immune responses. Adedokun et al. (2019) demonstrated that organic zinc supplementation influenced the antioxidant status and immune responses of broilers challenged with Eimeria tenella (Adedokun & Olojede, 2019). While a specific anticoccidial dosage is not solely attributed to zinc, adequate levels are important for overall immune competence, as highlighted by Jespersen (2023) (Jespersen, 2023).
Feed enzymes, such as carbohydrates and phytases, primarily improve nutrient digestibility. By enhancing digestion in the upper part of the digestive tract, they can reduce the amount of undigested nutrients reaching the hindgut, thereby limiting the substrate available for potentially harmful bacteria that can proliferate during a coccidiosis infection (Adedokun & Olojede, 2019; Alsayeqh & Abbas, 2023). A study investigated a combination of Quillaja and Yucca saponins (QY) in vaccinated broilers. At a dosage of 250 ppm in feed, QY complemented vaccination by reducing oocyst cycling and improving bird performance over a 42-day growth cycle (Bafundo et al., 2021).

Conclusion

In conclusion, nutrition plays a crucial role in managing coccidiosis in poultry production. Specific feed additives offer promising avenues for preventing and mitigating this disease. Through mechanisms such as direct antimicrobial action, modulation of the gut environment, and support of the bird's immune system, these nutritional interventions can contribute to improved poultry health and potentially reduce the reliance on traditional chemotherapeutic drugs.