The study included all females of fertile age over the 2002-2009 period, which were under the breeding control of the Association for Breeding Indigenous Breeds in Bulgaria. By using different methods of research, the breeding activity in the process of setting up an organizational structure of the Bulgarian Grey Cattle breed was assessed. The classical method of pure breeding with extended reproduction and stabilizing selection was applied. Habitats of distribution and separate breeding areas were formed by using the topographical method. The breed standard is updated and a rotation system of the breed sires was set up while avoiding unplanned inbreeding.
The increase of breed heads of the Bulgarian Grey Cattle through search activities is high (up to 57.34 per cent), while the expanded reproduction is from 12.63 to 29.54 per cent. The revised standard reflects the current state of development of the population and updates the requirements for including it in the Unified Registry of the breed. The areas in the breeding habitats were differentiated and the possibilities for variation of one full sire rotation cycle were defined.