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

Coccidia in chickens and turkeys, in addition to being an important disease in itself, is one of the main predisposing factors for necrotic enteritis (NE), a syndrome responsible for over 90% of the antibiotics used in Norwegian poultry production. The main goal of the TEiCON project is to facilitate and strengthen the sustainable development of Norwegian poultry meat production based on minimal use of antibiotics and coccidiostats. In this project, we aim to map coccidia in Norwegian broiler chickens and turkeys, both with and without intestinal diseases, and investigate which coccidia species are most important for disease development. Furthermore, we will identify strains of key coccidia species to determine whether certain strains cause more intestinal disease. We also aim to study the interaction between different coccidia species and the gut bacterium Clostridium perfringens in disease development. The results from TEiCON will be used by the Norwegian poultry industry and animal health authorities to gain a better understanding of which species and strains of coccidia cause intestinal diseases, and whether different species and strains affect chickens of different ages. Additionally, we will analyze a wide range of other data collected during sampling to uncover factors influencing disease outbreaks. This new knowledge will be used to implement measures to improve control of the most pathogenic coccidia species in Norwegian broiler poultry, thereby strengthening a farming system based on minimal use of antimicrobial agents. In the project, we have worked on planning and executing effective sampling for case/control flocks and the dynamic studies. Samples have been collected at different times for different flocks, for both turkeys and chickens. The industry partners contributed field veterinarians, who followed up on case/control flocks and selected flocks for the dynamic studies based on the project's criteria. Samples were sent to the Norwegian Veterinary Institute for laboratory analysis and were examined for Clostridium perfringens levels and the number of oocysts from coccidia, with the help of our diagnosticians. A protocol for DNA extraction was developed and thoroughly tested, and this protocol has also been synergistically used with good results in many other projects: SUSBROIL, BIOACTIVE, and TURKEYBIOME, to name three. Additionally, the TEiCON protocol with sampling and OPG/CFU has been successfully used in other projects/assignments. Molecular genetic investigations using quantitative PCR methodology, which allows for the identification of seven different Eimeria species found in chickens, have been completed. Screening with qPCR for seven species in turkeys is also well underway. Samples have been collected for biobank storage at the Norwegian Veterinary Institute's new biobank, allowing for the quick retrieval of samples for new analyses from long-term storage at -80°C. Field sampling began in September 2021 and was completed for chickens in 2023 for the three industry partners. Turkey sampling was completed in 2023. Quality assurance of the datasets, along with the collection of additional information to complement the sample data, was completed with the industry partners during the fall of 2024. Work on the collected chicken dataset has now started, and the data is currently being analyzed, while efforts to compile this work and the associated results into a publication have also begun.

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.