1. Vitagene and Health Research Centre, Bristol, BS4 2RS, United Kingdom.
2. Department of Hygiene and Poultry Sciences, Moscow State Academy of Veterinary Medicine and Biotechnology Named After K.I. Skryabin, 109472 Moscow, Russia.
3. Department of Microbiology and Biochemistry, Faculty of Veterinary Medicine, Trakia University, 6000 Stara Zagora, Bulgaria.
4. Department of Animal Nutrition, Faculty of Agricultural and Environmental Sciences, Szent Istvan University, 2103 Gödöllo, Hungary.
5. Saint-Petersburg State Academy of Veterinary Medicine, 196084 St. Petersburg, Russia.
6. All-Russian Institute of Poultry Husbandry, 141311 Sergiev Posad, Russia.