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Article History

Received: 11 December 2025

Accepted: 11 March 2026

First Online: 21 March 2026

Declarations

:

: The authors declare no competing interests.

: No animal was culled or immobilized for this study. Samples were collected on the occasion when animals were culled or immobilized for other reasons. Any lethal testing was carried out by local institutions responsible for European bison management, and each culling was performed with the necessary permit. The collection and storage of samples from dead animals was based on the decision of the Regional Director of Environmental Protection in Warsaw: according to this decision, no permission is needed for the collection of dead animals for scientific purposes. In addition, in accordance with II Local Ethical Committee for Animal Experiments in Warsaw, no approval was needed for ante-mortem sampling, as it was conducted as part of standard veterinary care. The care and use of animals were performed according with the Spanish Policy for Animal Protection RD 53/2013, which meets the European Union Directive 2010/63 on the protection of animals used for experimental and other scientific purposes.