Subject of inquiry. Cubs of the horned cattle of the meat breeds and their half-bred crossbreeds resulted from the insemination of crossing cows of the black-spotted breed with imported ones (kiansky, Aberdeen Angus, gerefordsk and sharolezkoyi). Different keeping systems and levels of energetic fodder of the Aberdeen Angus cub breeds. Object of the research. To determine functional state of the natural resistance and immunobiological reactivity of the organism of thorough bred cubs of the black-spotted, Aberdeen Angus, limuzynsk, gerefordsk, sementalsk of the meat breeds and half-bred crossbreeds resulted from the insemination of crossing cows of the black-spotted breed with bulls of kiansk, Aberdeen Angus, gerefordsk and sharolezkoyi breeds in the West Forest-steppe of Ukraine and also determine the state of the natural resistance and immunobiological reactivity of the organism of Aberdeen Angus cubs depending on the system of their growing and level of energetic fodder. Methods of research and equipment. Physiological, biochemical, clinical immunobiological, statistics. Photoelectrocolorimeter, centrifuge, microscope. Scientific newness of the obtained results. For the first time functional state of animal organism was determined depending on natural resistance of the thorough bred cubs of the Aberdeen Angus, limuzynsk, gerefordsk and meat sementalsk breeds resulted from the embryo transplantation from Canada beard by the cows at farms. As well as half-bred crossbreeds resulted from the insemination of crossing cows of the black-spotted breed with bulls of kiansk, Aberdeen Angus, gerefordsk and sharolezkoyi breeds in the West Forest-steppe of Ukraine. Besides, during the work natural resistance of Aberdeen Angus cub breeds depending on zoo-hygienic keeping systems and levels of energetic fodder was determined. It is determined that natural resistance of the thorough bred cubs of the meat breeds at all ages was apparently lower than in black-spotted coeval and level of the natural resistance of the half-bred crossbreeds beginning from the 6-th month age was higher comparing with thorough bred cubs of the black-spotted breed. It is also defined that keeping bulls of Aberdeen Angus breed in the premises protected from wind helped to increase natural resistance at the same time unbalanced feeding reduces natural resistance during winter period much more than during summer. Thus, incensement of the natural resistance during winter period as well as during summer did not influence natural resistance of the Aberdeen Angus cubs' breed. Subject and degree of achievement application. To improve functioning of the meat breeds cub organism thorough bred cubs of the Aberdeen Angus and gerefordsk breeds were used as well as half-bred crossbreeds with black-spotted. Cubs of the Aberdeen Angus breed should be kept in simple premises protected from wind. The level of the energetic fodder of meat breed cattle should be secured 115-120% more from existing ones. Effectiveness of achievement application: Research results fromthe point of view of immunobiological status of the meat breed cattle are used in educational programs for raising the level of skills of veterinary medicine doctors, animal scientists and also used by the workers of veterinary medicine and animal science services in Slavutsk, Derazhnyansk and Polonsk districts of Khmelnytsky region while working with thorough bred and crossbreed animals of the specialized meat breeds. Field (branch)of application: in cattle breeding, in educational process, teach physiology of cattle for students of Agrarian Institutions of III-IV levels of accreditation.
