| dc.description.abstract | Commercial pig producers use artificial insemination (AI) extensively for breeding purposes. Successful outcome of AI practices is thus extremely important. Several factors important for successful fertilization, healthy embryo, and progeny development affect AI's efficiency. High-quality sperm are essential for successful fertility as AI centres use fewer spermatozoa per AI than those available by natural mating. AI centres commonly use liquid-preserved boar semen, and methods for choosing high-quality semen are important. The purpose of this thesis was to investigate potential improvements in the quality of boar semen by utilizing various techniques for semen processing and preservation. Single Layer Centrifugation (SLC) is a technique that has been developed to separate the best quality spermatozoa from semen samples. Moreover, due to the lipid composition of the plasma membrane, boar sperm is extremely susceptible to cold shock. Comparing the quality of sperm cells applying two freezing procedures was therefore included in this project.
The SLC method was used to select high-quality sperm of two breeds (Landrace and Duroc) over a period of six days storage at 18 ℃. The experiments were performed on the day of collection (Day 0) and after 3 and 6 days of storage at two different ages of the individuals included. Sperm quality evaluations included motility, viability, acrosome integrity, DNA integrity, and ATP content. The cryopreservation experiment was conducted by diluting the semen samples of Landrace and Duroc in lactose egg yolk extender and frozen in medium plastic straws by two different cryopreservation procedures: programmed freezing by IceCube and freezing in liquid nitrogen vapor. The quality of the sperm during the cooling phase (before freezing) and after thawing was evaluated.
Results of the assessment of SLC's impact on boar semen quality (both breeds) at both ages indicated that progressive motility, ATP content, viability, and acrosome integrity were mostly be enhanced in SLC samples, whereas hyperactive proportion, DFI%, and HDS% demonstrated a decline in comparison to those without SLC treatment. Comparing post-thaw samples revealed that there were some variations in male individual sperm quality; the programmed freezing demonstrated a better outcome than the freezing in liquid nitrogen vapor. For both Landrace and Duroc, the proportion of total and progressive motility as well as AIL% post-thaw IceCube samples were higher than those directly exposed to liquid nitrogen vapor. When it comes to cryopreserving boar semen, the applied programmable method showed better post-thaw sperm quality than the other method tested. | |
