Influence of some factors on stud bulls reproductive capacity in Krasnoyarsk region

The aim of the study is to investigate the reproductive capacity of stud bulls of AO Kras-noyarskagroplem. Objectives: to analyze sperm production indicators taking into account the breed, linear affiliation and ecogenesis of bulls; the ability of bull sperm to deep freezing; fertilizing ability and calving results of cows. The object of the study were stud bulls of AO Krasnoyarskagroplem of the red-and-white (n = 4) and Holstein (n = 11) breeds in the period 2014–2019, having different ecogenesis. The material was the sperm production of the stud bulls. The sperm indicators were assessed in accordance with GOSTs. The fertilizing ability and calving results of cows on farms in the Krasnoyarsk Region were carried out using the IAS SELEKS – Dairy Cattle. Breeding accounting in farms. On average, Holstein bulls pro-duced 38.4% more ejaculates per year (P > 0.95), but their ejaculate volume was 12.5 % less than that of red-and-white bulls. The Holstein bull Kompas 9080 had a low sperm concentration of 0.97 billion/ml, with an average activity of 79 % and a native semen rejection rate of 9.7 %. The largest amount of native se-men was rejected from the bulls Tiger 9189 and Ural 20751 – 26.9 and 22.6 %, respectively. The red-and-white bull Volan 17436 also had a low sperm concentration of 1.08 billion/ml. The highest ejaculate volume was produced by the bull Polet 28345 – 5.46 ml. Bulls born in the Krasnoyarsk Region produced 7.5 % (P > 0.99) more ejaculate volume than bulls born in the Netherlands. Spermatozoa obtained from Holstein bulls tolerated deep cooling worse, since after defrosting 9.9 % (P > 0.95) of sperm doses were rejected due to poor survival. The proportion of cows fruitfully inseminated from the first insemination averaged 72 %. Stillborn calves were most often born from the bull Radon 11764 of the V.B. Ideal line and the bull Variant 21682 of the S.T. Rokit line.