Coccidiosis and histomoniasis are economically significant diseases in chickens and turkeys. Management, vaccination and medication are key tools in the control of these diseases but these tools are not without challenges. Work undertaken in both the laboratory and the field has looked at the impact of oregano-based (Orego-Stim) and carrier-based organic acid products on the prevalence of Eimeria infections or histomoniasis. Data indicate that Orego-Stim and/or organic acid presented in feed are able to positively influence bird performance during periods of exposure to Eimeria and, to a lesser extent, Histomonas. Early indications suggest these two types of additives might have an integral role in protozoal management programmes.
Eimeria and Histomonas are responsible for two of the main protozoal diseases that affect poultry: coccidiosis and Blackhead (histomoniasis). The economic impact of these diseases can be severe. For example, coccidiosis is estimated to cost the US poultry industry $127 million annually. Turkeys appear to be more susceptible to Histomonas meleagridis than chickens, where if left untreated, it can cause mortality approaching 100%. There is also some suggestion that the virulence of Histomonas is affected by the presence of bacteria, notably Escherichia coli, Clostridium spp. and Bacillus subtilis, indicating, perhaps, a relationship with the gut, and particularly caecal, microbiota.
Antiprotozoal drugs and vaccines have long been used in commercial poultry production but there are no new compounds coming to market. With the withdrawal of some existing products as well, the tools to help manage protozoal poultry infections are becoming limited. Feed additives, such as those based on organic acids or essential oils are increasingly used in poultry production as alternatives for antibiotics and to help manage gut microbiota. Can such products also help in the management of protozoal diseases, where gut health is known to be a significant factor?
Oregano, organic acids and coccidiosis
The use of oregano oil in laboratory infections with Eimeria has been well documented with promising results, although typically the studies are run in laboratory settings on clean litter systems. Recent work at Southern Poultry Research (Georgia, USA) demonstrated synergy between a commercial oregano-based product (Orego-Stim, OS) in feed and a commercial anticoccidial vaccine (Coccivac B52, Merck, USA). Birds were reared on re-used litter (to ensure a high natural bacterial and protozoal challenge) for 42 days and given a mixed Eimeria sp. (Eimeria acervulina, E. maxima and E. tenella) challenge at 21 days of age. Where hatchery vaccination with a anticoccidial vaccine significantly adversely affected performance relative to a salinomycin (60 ppm) treatment (FCR: 1.87 and 1.64, Weight gain: 1.917 kg and 2.375 kg, respectively), the inclusion of OS at 150 g/T in feed was able to significantly ameliorate the vaccines negative performance impact (FCR: 1.73, Weight gain: 2.194 kg) without adversely impacting immune status to coccidial challenge (Figure 1). Indeed, OS (450 g/T) on its own delivered similar performance to salinomycin (FCR: 1.67, Weight gain: 2.412 kg).
Oregano and histomoniasis: field observations
Conclusions
Feed additives have an important role in managing gut health in poultry production. Laboratory and field experience support the potential of a commercial oregano-based product, Orego-Stim, alone or in combination with a carrier-based organic acid to have a significant role in protozoal (Eimeria and Histomonas) management programmes. More work is necessary to explore and understand their potential further.
References are available on request. 65th Western Poultry Disease Conference