Morphological and morphometric characteristics of fresh and cryopreserved spermatozoa of saanen bucks

Background. Cryopreservation of spermatozoa with the best morphofunctional characteristics may allow their use for assisted reproductive technologies in goat breeding throughout the year to effectively increase livestock. Aim. To evaluate the influence of seasons on morphological and morphometric characteristics of fresh and cryopreserved goat sperm. Methods. The ejaculate samples of three sexually mature bucks of the Saanen breed were obtained during the breeding and non-breeding seasons. To assess the morphological characteristics, the smears of sperm were stained and then visualized under a light microscope with a magnification of ×1,000. For morphometric measurements, sperm micrographs were taken and analyzed using the ImageJ software. The cryopreservation of sperm was performed in a medium with 10 % glycerol and 20 % egg yolk. The samples were thawed in a water bath, then the morphological and morphometric characteristics of the cells were evaluated. Results. After the cryopreservation, the number of sperm with abnormal morphological structures was significantly higher compared to fresh sperm, both in the breeding and non-breeding seasons (p ≤ 0.05). After the cryopreservation, the length and width of the head decreased significantly (p ≤ 0.05) compared to the corresponding sperm sizes before the cryopreservation. Analyzing the morphological char- acteristics of the tail part, we revealed the fact of its reduction after the cryopreservation, probably due to twisting, loop formation, and detachment of its part. Conclusions. It was found that in the non-breeding season, the number of spermatozoa with damaged morphological structures increases, compared to the breeding season, which must be taken into account when using reproductive technologies. The morphological and morphometric characteristics of Saanen buck spermatozoa change after the cryopreservation, regardless of the season, which indicates the need to choose the fertilization tactics that will ensure the selection of spermatozoa without any morphological abnormalities.