Comparative analysis of cryopreserved ram sperm parameters depending on the dilution medium

Abstract

To improve the effectiveness of long-term sperm storage outside the animal’s body, it is necessary to enhance the protective media that help reduce the impact of cryodamaging factors on sperm. In this study, sperm from Assaf breed rams was used. Sperm was collected from the rams twice a week using an artificial vagina, which ensured high-quality material. For analysis, ejaculates with at least 70% motility and a concentration of 2,0 to 2,5 billion sperm per milliliter were selected. The aim of the study was to compare the parameters of cryopreserved sperm depending on the synthetic media used: GTJ, STJ+MP, and STJ+IMB-2. This allowed for the determination of the most suitable extender to ensure a higher fertilization rate. During the study, the main parameters of cryopreserved sperm were analyzed, including motility, percentage of pathological sperm forms, plasma membrane integrity (based on the hypoosmotic swelling test results), and acrosome integrity. The highest values were achieved with samples diluted with the STJ+IMB-2 medium. In this group, the following results were obtained: motility – 54,0±0,4%, velocity (VAP) – 91,8±3,4%, VSL – 75,5±3,9%, VCL – 132,0±3,8%, percentage of anomalies – 16,75%, acrosome integrity – 24,15±0,31%, and plasma membrane integrity was 65,6±0.7%. The obtained data suggest that the STJ+IMB-2 medium provided the most effective protection for sperm during cryopreservation compared to other media such as GTJ and STJ+MP. These results highlight the importance of selecting an appropriate medium to optimize cryopreservation processes and improve fertilization rates.