Evaluation of semen parameters from Fleckvieh-Simmental bulls and the influence of age and season of collection.

The aim of this paper was to evaluate semen parameters from Czech Fleckvieh (dual-purpose breed) bulls used in artificial insemination in the Fleckvieh population. The ejaculate was collected from bulls only once a week, which is not usual. Respectively, the effects of age and season of collection on semen parameters were tested. The average volume of ejaculate by Fleckvieh bulls was 8.72 mL, which is higher than results in studies of bulls which were collected usually more than once a week. The average total motility was 72.82 % and progressive motility was 67.99 %. Sperm concentration reached on average $1254.10\times {10}^6$   ${\mathrm{mL}}^{-1}$ . The total motility of spermatozoa after thawing was 40.88 %. A significant influence of age was observed on ejaculate volume, total and progressive motility, and total motility after thawing ( $P<0.05$ ). The season of collection had a significant influence on the volume of ejaculate, total motility, progressive motility, concentration of spermatozoa, and total count of spermatozoa ( $P<0.01$ ).