Developing tools to optimize the control of coccidiosis without use of antimicrobials

Coccidiosis is a potentially severe intestinal disease in broilers and turkeys, and it is an important predisposing factor for necrotic enteritis.Treatment of necrotic enteritis accounts for more than 90 % of all therapeutic antibiotic use in Norwegian poultry production. The main objective of Tools for Eimeria Control (TEiCON) is to reinforce a sustainable development of the Norwegian poultry meat production based on a minimal use of antibiotics and in-feed anticoccidials. We will screen Norwegian broilers and turkeys with and without intestinal disease for abundance of coccidia, and investigate which species of coccidia are the most important in causing intestinal disease. Furthermore, we want to identify different strains within important coccidia species, and detect which strains are most likely to cause disease. We also want to study the role of the interplay between different coccidia and the intestinal bacterium Clostridium perfringens in intestinal disease. The results of TEiCON will be used by the Norwegian poultry meat industry and Norwegian animal health authorities to gain a much better understanding of which species and strains of coccidia are causing intestinal disease, and if different species and strains affect different age groups of birds. This new knowledge will be used to take measures to improve the control of the most important disease-causing coccidia species and strains in Norwegian broilers and turkeys, and thus reinforce a farming system based on minimal use of antimicrobials. We have designed field sampling strategies for case and control flocks and for dynamic studies, sampling at several time points for selected flocks for both broiler and turkeys. The industry partners with their field veterinarians select the case and control flocks, appoint the flocks for dynamic studies and ensure that farmers send samples to the Norwegian Veterinary institute. The samples are analysed for the presence and level of Cl. perfringens and the number of coccidian oocysts is assessed by a microscopic method by our collaborating diagnostic team. Molecular screening of samples by qPCR targeting the common chicken Eimeria spp. have started.. In addition, parallel samples will be stored in a Biobank for future studies using high throughput sequencing. The field sampling started in September 2021 and will be ongoing for approximately one year. TEiCON was introduced at the Nordic Poultry Conference on November 10, 2021 in a presentation held by dr. Silje Granstad. The title of the presentation was ?Poultry Health Status in Norway 2020 ? 2021?, and TEiCON was presented as the chief ongoing poultry health-related research project at the Norwegian Veterinary Institute. The conference gathered more than 230 participants from 10 different countries.

The main objective of ‘Tools for Eimeria Control’ (TEiCON) is to reinforce a sustainable development of the Norwegian poultry meat production based on a minimal use of therapeutic antibiotics and in-feed anticoccidials. To this end the project will pursue a number of sub-goals. We will screen Norwegian broilers and turkeys with and without intestinal disease for abundance of protozoan Eimeria species, and investigate the association between Eimeria species and intestinal health. TEiCON will examine Eimeria species for genetic markers of strain differences, and examine if different strains are associated with different state of intestinal health. We will characterize isolates of the intestinal bacterium Clostridium perfringens from turkeys, and study the interplay between Eimeria strains and Clostridium perfringens in their impact on intestinal disease. Strain identification is important because different Eimeria strains within same species may vary substantially in terms of capability to induce disease. However, identifying the optimal strain marker with regard to disease-inducing property is not straightforward, and may require the use of several approaches. Differentiating between vaccine strains and field strains of Eimeria is another challenge that is important to overcome in order to understand the Eimeria epidemiology of flocks vaccinated with live vaccines. The results of TEiCON will be used by the Norwegian poultry meat industry and Norwegian animal health authorities to gain a much better understanding of which species and strains of Eimeria are causing intestinal disease, and if different species and strains affect different age groups of birds. This new knowledge will be used to take measures to improve the control of the most important disease-causing Eimeria species and strains in Norwegian broilers and turkeys, and thus reinforce a farming system based on minimal use of antimicrobials.