Coccidiosis of ruminants has a lower direct impact on animal health compared to the bird species. Nevertheless, it is able to induce significant effects on animal productivity and health, in both large and small ruminants, mainly in its sub clinical form.
Essential oils are aromatic substances extracted through steam distillation from different herbal plants. According to the 2002/C329/EC directive, essential oils are currently and quite commonly used as feed additives in the livestock industry, especially as flavouring and appetising substances. Some etheric oils extracted from aromatic plants, namely from selected strains of Origanum vulgare have shown antibacterial properties based on the impairment of the bacterial cell membrane, by changing its permeability to cations, such as H+ and K+, causing water imbalance and cell death.
Because of this mode of action, resistance to phenols is unlikely to develop. In addition to the antibacterial activities of oregano extract, anticoccidial properties have also been found.
In the normal intestinal mucosae, the epithelial lining is regularly shed, and replacement occurs by cell division from within the crypts. Phenols act on the gut lining by increasing the rate of enterocyte turnover about two times of the normal rate.
In coccidiosis, infection occurs when birds ingest sporulated oocyst from the litter. This is followed by a period of asexual development (schizogony) and then by a sexual phase (gametogony), wherein the parasites multiply in the epithelial cells of the intestine.
Phenols such as those in oregano extract disrupt the life cycle of coccidian parasites by speeding up the rate of shedding of the gut lining. By this mode of action, intracellular coccidia sporozoites are shed before they have the opportunity to penetrate deeper into the gut wall or form new oocysts. Oregano extract therefore prevents or controls clinical coccidiosis by creating an environment that is hostile to the completion of the life cycle of the parasite.
This mode of action is very close to that of ionophores antibiotics, such as monensin and salinomycin, that have been used as antibiotic growth promoters as well as coccidiostats worldwide.
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Article made possible through the contribution of Meriden Animal Health.