1 Vitagene and Health Research Centre, Bristol BS4 2RS, UK.
2 Department of Hygiene and Poultry Sciences, Moscow State Academy of Veterinary Medicine and Biotechnology named after K.I. Skryabin, Moscow 109472, Russia.
3 Department of Microbiology and Biochemistry, Faculty of Veterinary Medicine, Trakia University, Stara Zagora 6000, Bulgaria.
4 Department of Animal Nutrition, Faculty of Agricultural and Environmental Sciences, Szent Istvan University, Gödöllo H-2103, Hungary.
5 Saint-Petersburg State Academy of Veterinary Medicine, St. Petersburg 196084, Russia.