Bovine spermatozoal head size variation and evaluation of a separation technique based on this size.

The objectives of this study were to determine the variation of head areas of normal spermatozoa attributable to breed, individual bull and ejaculate and to verify separation of X and Y chromosome-bearing spermatozoa and separation effectiveness. Spermatozoa were evaluated using video enhanced contrast microscopy combined with video intensified fluorescent microscopy and the polymerase chain reaction (PCR). In Experiment 1, spermatozoal head areas were measured from 2 ejaculates collected from bulls of 3 beef and 2 dairy breeds. No differences in head areas were found between breeds or between bulls within breeds; variation was observed among ejaculates from individual bulls across breeds. In Experiment 2, spermatozoa from 5 ejaculates were separated on individual SEPDEVICEs (Patented). Head area, fluorescent intensity and PCR of spermatozoa retained in the SEPDEVICEs suggested a separation based on size in 1 of 5 samples. Ejaculate variation in head areas affected separation efficiency.