Chumak E. Natural resistance of Texel sheep breed and their crossbreeds under the ecological and farming conditions of Ukraine steppe zone.

The thesis is concerned with the problem of data received on the basis of complex sanitary, physiological, biochemical and zootechnical research about the biological peculiarities of Texel sheep breed, Askaniya meat and wool sheep breed of Dnipropetrovs'k type, as well as received from them hybrids of the first generation with the theoretical grounding and evaluating the state of natural resistance of Texel sheep breed with adaptation to the ecological and farming conditions of Ukraine steppe zone. The received materials give an opportunity to ground the expediency of using Texel rams in the process of selection to improve the population productivity of Texel sheep breed, Askaniya meat and wool sheep breed of Dnipropetrovs'k type. Herewith, according to the data of natural resistance, immunological reactivity, breathing, gas and energy metabolism and heat resistance the positive adaptation possibility of the first generation crossbreed young animals, received from crossing the dams of the local, Dnipropetrovs'k type with the imported Texel rams breed to the regional ecological and farming conditions of Ukraine steppe zone - the natural habitat of their future breeding, is proved. The new information about the indices of different rams genotypes slaughtering as well as the peculiarities of crossbreed young sheep breed Texel's growth and development under the conditions of the local environment is received.