Zhukorskiy O. Ecological fundamentals of beef production and mechanisms of beef productivity forming in cattle.

The dissertation features peculiarities of forming beef productivity in beef young stock of dairy cattle, beef breeds and their crossbreeds of various age under the influence of ecological factors of natural climatic conditions in Ukraine's West Forest - steppe. The paper defines preconditions of transition to organic production of beef in the experimental region. These preconditions are based on the use of aboriginal combined and home newbred beef breeds as well as on new technological methods of pasture maintenance of cattle young stock, which help to reduce the effects of technological and stressful factors. The mechanisms of genetic potential manifestation in these breeds' beef productivity and their crossbreeds have been studied on the ground of the animal's functional state of the organism, morpho-biochemical, immune blood indexes, growth indexes and beef productivity. Considerable variability of physiological reactivity which is of seasonal, weather-climatic, breed and age character has been defined. The succession of physiological reactivity and the forming of the productive state of the cattle young stock under the influence of meteorological environmental conditions has been studied. Age growth peculiarities of beef productivity, interior indexes and behavioral peculiarities of young bulls of beef and dairy breeds and their crossbreeds on organic breeding technology have been defined.