Lukyanchuk N. 3. Assessment the optimum age of breeding use for Ukrainian beef breed

Object - animal of various sex and age groups of Ukrainian beef breed of cattle. Purpose - to improve the elements of technology of obtaining and breeding use of cows of Ukrainian beef breed on the basis the optimum of calving age estimation. Methods - zootechnical and statistical.Novelty - effect of average maternal age (5,1-9 years) on increase the live weight of steers and decrease of sires semen performance has been estimated. Assumption about decrease of milking and reproduction abilities, calf survival at weaning of the cows older then 9 years of age got its further development. The new data has been obtained about the influence of mother's age on the increase heifers live weight, improvement of cows' reproduction performance and longevity. Divergent effects of maternal age on son's and daughters' reproduction performance have been found. Results of researches - are used in practice scientific process and research work. Branch - animal industries.