EN
Artificial insemination is widely used in cattle reproduction all over the world and enables rapid genetic improvement in cattle breeding. The extent and importance of artificial insemination has significantly increased since semen storage in liquid nitrogen was introduced into practice. Semen may be stored for years in this temperature with no negative impact on its quality. However, infectious agents such as viruses also survive for very long time at the temperature of liquid nitrogen. For this reason it is vital to ascertain that breeding bulls are free from viral infections before collecting semen otherwise they could cause a large scale spreading of infectious diseases in cattle populations. The aim of the article is to provide readers with information about the most important cattle viruses which can be transmitted by bull semen.