There is an increasing concern about losing genetic diversity in farm animals, and poultry genetic resources are considered to be one of the most endangered (Crawford, 1990). A large number of local dual-purpose breeds used at the beginning of the last century have been replaced with highly specialised lines. Market orientated intensive livestock breeding programs tend to concentrate on just a limited number of breeds, and the proportion of low-input, low-output breeds used in agricultural production in developed countries has been decreased almost to zero. Decreasing numbers of breeds results in reduced genetic variability, and limits the flexibility of future breeding programs. On the other hand, an increase in income in these countries leads to a rise in demands for specialised food, diversification in the product supply, and changes in preferences of production conditions.