Sperm morphology in Estonian Holstein Dairy Bulls, factors affecting it and relations to fertility
2002
Padrik, P. | Jaakma, Ue. (Academical Agricultural Society, Tartu (Estonia))
Effective milk production does not depend only on valuable genetics of dairy cows but also on many other factors including optimal calving interval. Conception of cows after calving is significantly influenced by the quality of frozen bull semen. The aim of the current study was to evaluate sperm morphology of Estonian Holstein bulls, the factors influencing it and the correlation between the percentage of normal spermatozoa in fresh semen and bulls' in vivo fertility expressed as non-return rate (NRR) of dairy cows and heifers. The results of the study showed that increase in bulls' age was accompanied by the significant increase in the incidence of sperm abnormalities. The highest incidence of sperm abnormalities was detected in the semen of 6-7 years old bulls. Frequency of sperm abnormalities in fresh semen varied also between the seasons. The incidence of abnormal spermatozoa was the highest in ejaculates collected in summer, from June to August. The bulls with the CVM-carriers in their pedigree during previous three generations had more abnormal spermatozoa in the fresh semen that control bulls
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