Relationship Between Apoptotic-Like Changes in Stored Boar Semen and DNA Fragmentation in Preimplantation Embryos

The aim of this experiment was to study the relationship between apoptotic-like changes in spermatozoa and DNA fragmentation in embryos obtained after insemination with fresh and stored semen. The ejaculates collected from three boars (five ejaculates from the same boar) were extended in Biosolwens Plus extender and stored for five days at 15-17°C. Semen, both fresh (Day 0) and stored (Day 5) used for insemination was analysed to detect apoptotic-like changes using fluorescence method: an assay to assess early changes in the membrane integrity of the sperm using the YO-PRO-1 fluorophore. After 5.5 days of insemination embryos were flushed out of the uterus and DNA fragmentation using TUNEL was analysed. In the fresh semen an average of 2.7, 3.7 and 6.2% of apoptotic sperm was observed in boar nos. 1, 2 and 3, respectively. After five days of storage the percentage of apoptotic sperm significantly increased up to 8.0, 15.7 and 23.2% in each analysed boar. The TUNEL index was 7.1% in the morphologically normal expanded blastocysts obtained after insemination with stored semen, and approximately 1.7% after insemination with fresh semen. A greater number of degenerated embryos and higher incidence of DNA fragmentation in the morphologically normal blastocysts were observed after insemination with stored semen which consists of higher percentage of apoptotic sperm compared to results from insemination with fresh semen.