1. Department of Animal Reproduction Biotechnology and Environmental Hygiene ,
2. Laboratory of Biostatistics , Faculty of Biotechnology and Animal Husbandry , West Pomeranian University of Technology in Szczecin , 71-270 Szczecin , Poland
3. Biebrza National Park, Osowiec-Twierdza 8, 19-110 Goniądz , Poland