1. 1 Executive Agency for Selection and Reproduction in Animal Breeding, Sofia, Bulgaria
2. 2 Stud Farm Karadjordjevo, Karadjordjevo, Serbia
3. 3 Scientific Center of Agriculture, Agricultural Academy, Sredets, Bulgaria
4. 4 Research Centеr of Stockbreeding and Agriculture, Agricultural Academy, Smolyan, Bulgaria
5. 5 Department of Animal Diversity and Resources, Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, ‘Acad. G. Bonchev’ Str., Bl. 25, 1113, Sofia, Bulgaria