Optimisation and characterisation of boar epididymal sperm retrieval, handling and preservation using computer-assisted sperm morphometry: implications for cryopreservation and in vitro fertilisation.

Abstract

The possibility of epididymal sperm recovery at post-mortem has drawn more attention due to the desire to protect endangered species. This study aimed to characterise boar epididymal sperm morphometry and motility before and post cryopreservation, using computer-assisted sperm analysis. In the first experiment, the effects of sperm retrieval techniques and extenders were compared on the epididymal sperm motility and morphometric traits. Results suggest that the slicing float-up technique is the choice to obtain viable sperm from boar epididymis. In the second experiment, the effects of time elapsed between the animal’s death and sperm recovery on sperm motility and morphometry traits of boar cauda epididymides stored at 5 and 18 °C were investigated. It was concluded that boar epididymal sperm retrieved from the testes stored at 5 °C until 72 h post-mortem can maintain their total motility and morphometry. However, more sperm with greater motility and normal morphometry were recorded after 2 h post-mortem from the testes stored at 5 °C. In the third experiment, the effects of in vitro liquid semen preservation period and temperatures (5 and 18 °C) were investigated on boar epididymal sperm changes in terms of sperm motility and morphometry. It was concluded that storage at 18 °C can maintain boar epididymal sperm total motility and morphometry up to 48 h. In the fourth experiment, the effects of semen holding time at 18 °C on the quality and cryo-tolerance of boar epididymal sperm were investigated. It was concluded that holding time of 3 h at 18 °C improved the cryo-tolerance of boar epididymal sperm motility and morphometry. In the fifth experiment, the in vitro fertilisation potential of post-thawed boar epididymal sperm was investigated utilising pig oocytes that have undergone maturation in North Carolina State University 23 (NCSU-23) and modified NCSU-23 media. The modified NCSU-23 media was prepared with double amount of the required glucose concentration excluding sorbitol. The findings revealed that the fertilisation rate was achieved using oocytes matured with both NCSU-23 and modified NCSU-23 media. This study contributes to the advancement of reproductive biotechnology and the conservation of valuable or endangered genetic lines.