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Productivity and reproduction of herd have influence on dairy cattle herd profitability. Reproduction traits are dependent from genetic and non genetic factors. For improvement of breed, aspiring to increase productivity of dairy cows, the bulls having large amount of Holstein genes are used. The aim of the study - to test the influence of Holstein genes in bulls' genotype on the reproduction traits of their daughters: age at the first calving, days open, calving interval, number of services from calving to conception and calvings results. The information of a pedigree, calvings, inseminations, and part of genes of improving breed in a genotype of bulls of black and white cattle in Lithuania was used. In Lithuania, to improve dairy cattle productivity, bulls having large amount of Holstein genes are used. As a result of such selection work we have productive cows, which have days open, number of services from calving to conception and calving interval larger than cows, which have not been improved with Holstein breed genes and characterized by lower productivity. In order to avoid reproduction problems it is very important to choose the optimal time for insemination after calving, taking into account productivity of cows. [ABSTRACT FROM AUTHOR]