The index of DNA fragmentation in sperm chromatin as a criteria to predict an individual fecundity in bulls sires

A biological value of sperm, and, in particular, the intactness of genetic material are of the main importance for normal fecundity in males. To check the destructive changes of sperm chromatin, a DNA fragmentation index (FI) was estimated in frozen and thawed sperm samples of bulls of different breeds from the collection of the Laboratory of cryobiology, All-Russian Research Institute for Animal Breeding. The AO test with acridine orange (AO) as a staining agent was used. The index value was shown to depend on several factors and vary from 0.96 to 80 %. According to their FI values, the tested bulls were divided into four groups of high, middle, moderate and minimal fragmentation level with FI > 30.01 %, from 10.01 to 30.0 %, from 5.01 to 10.0 % and