Influence of HeiferPlusTM treatment on some functional parameters of frozen-thawed bovine spermatozoa assessed by flow cytometry.

HeiferPlusTM is a new sperm sexing agent used to increase the percentage of heifer calves in dairy and beef cattle by enhancing the fertility and the motility of the X-chromosome bearing sperm. The aim of this study was to assess the influence of HeiferPlusTM treatment on sperm functional parameters of frozen-thawed bovine spermatozoa assessed by cytofluorimetric analysis such as sperm viability (by using propidium iodide probe), acrosome reaction (by using PNA-FITC probe), sperm chromatin stability (by using acridine orange probe) basal ROS determination (by using DCFH-DA probe) and mitochondrial activity (by using JC-1 probe). The HeiferPlusTM treatment induced a significant (p<0.05) reduction of: sperm viability, basal ROS level and mitochondrial function, while sperm chromatin stability, measured as %-DNA fragmentation index (DFI), mean DFI and SD-DFI was not affected by the treatment. Concerning acrosome reaction, it was already observed a significant increase (p<0.05) of reacted live spermatozoa after 1,5 h incubation in either the presence or absence of Ca2+ in the semen treated with HeiferPlusTM compared to 0 h, while in the untreated semen the increase of reacted live spermatozoa was observed only after 3h incubation in presence of Ca2+. The treatment seems to affect some functional parameter of bull spermatozoa and to anticipate acrosome reaction.