Browsing by Author "Bitseit Lukas"

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    Cooling Tolerance and Post-Thaw Quality of Bovine Epididymal Spermatozoa After Vitrification Using TrisCitrate-Sucrose Based Extender
    (Addis Abeba University, 2024) Bitseit Lukas; Fekadu Regassa; Haileleul Negussie
    Cryopreservation involves preserving living cells, such as sperm, at very low temperatures to maintain their viability for extended periods, particularly in breeding animals. An experimental investigation was conducted between December 2023 and May 2024 aimed to assess the efficacy of a specific extender media-cryopreservation combination method for evaluating the quality of epididymal sperm under field conditions. The cooling tolerance of bull epididymal spermatozoa preserved in a homemade tris-citrate-sucrose extender media was evaluated. Further, the impact of two methods of vitrification (direct droplet and straw) on post-thaw sperm quality and the effect of supplementing high (12.8%) and low (2.5%) glycerol to the base media on cryosurvival were evaluated. All physical parameters including body weight, BCS, scrotal circumference and other testicular measurements were recorded. Mean scrotal circumference, size and volume of the testis were 32.06±1.2cm; 301.80±37.4g and 334.86±105.1cm3 , respectively. Pre-freeze motilities were generally higher (76.88% mass motility and 73.13% individual motility). A significant difference (P<0.05) in motility was generally observed between pre-freeze and post-freeze samples. Nevertheless, a very high cooling tolerance was evident during the first 30-minute cooling period with no significant difference (70%, p>0.05) in motility from prefreeze values. But a drastic 23% drop in motility was observed after 60 minutes, indicating declining cooling tolerance over time. Testicular and epididymal weight and scrotal circumference were significantly associated with improved sperm motility, suggesting that bulls with higher scores in these parameters tend to have higher sperm motility. Spermatozoa destined for vitrification showed significantly higher (P<0.05) pre-freeze motility, with the head region exhibiting a higher number of morphological defects than the tail. Glycerol concentration (2.5% and 12.85) in vitrified sperm had a significant role (P<0.05) in post thaw sperm parameters with higher concentrations improving cryocervival. Vitrification method also had a significant role in postthaw sperm parameters with straw vitrification in high glycerol (12.8%) having better impact in cryocervival compared to direct vitrification with lower glycerol (2.5%). In conclusion the recovery and cryopreservation of epididymal sperm from live or dead animals is a viable option in maintaining their germplasm available for future use. Further, the freezing technique is a promising method for field application particularly in evaluating preservice bulls before purchase.