In the conditions of the Republic of Belarus there was realized the evaluation of genetic inheritance indexes of producing bulls at a cattle breeding enterprise in Belarus depending on a selection source (in accordance with an average productivity of female ancestors) in order to use them properly for the increasing of genetic potential of black-and-white Belarusian cows in Gomel region. The carried out analysis allowed to draw a conclusion, that bulls of national breeding lines according to the indexes of cow milk yields concede foreign bulls, i.e. delivered of Sweden on 2744 kg of milk or on 27,5% and from Russia and Hungary - on 1272-2906 kg of milk or 12,7-29,1% (Р less than 0,001). In accordance with butter-fat yielding capacity of bull mothers obtained at breeding farms of Belarus and in accordance with groups delivered from the other countries there were stated no essential distinctions (0,05). Butter-fat yielding capacity percentage of bull mothers varied within 3,99-4,10%. However, the yield of dairy fat per lactation the difference was in favour of bull mothers delivered from Sweden (114 kg or 27,9%) at P less than 0,001. Distinctions on milk producing ability of bull mothers from various cattle breeding enterprises of Belarus were revealed. It was established, that at mothers of bulls delivered from Hungary the variability of milk yield was the highest (3032 kg or 23%). Low variability indexes of milk yield and butter-fat yielding capacity percentage was typical for bull mothers of the Belarusian selection. The standard deviation at them made 872 kg of milk yield with 9% variability coefficient, and 0,03% - for butter-fat yield and 7% respectively. Variability on all indicators of dairy efficiency of bull mothers from various cattle breeding enterprises of Belarus in most of the cases was low - from 2,3 to 13%.