Sperm concentration and viability of bull semen frozen in 2004-2010, from the collection of the National Bank of Biological Material.

The aim of this study was to carry out a follow-up evaluation of cryopreserved semen of native breed cattle collected in the National Bank of Biological Material (NBBM). The oldest material, from 2004-2010, was included in the study. A total of 70 ejaculates from 62 bulls (5 Polish Red-and-White, 7 Polish Black-and-White, 11 Whitebacked, 39 Polish Red) were used in the study. After thawing sperm concentration and viability (plasma membrane intactness) were determined using a fluorescence-based instrument - NucleoCounter SP-100. Sperm concentration was higher (p≤0.05) for the semen of Polish Red-and-White and Polish Red bulls compared to the semen of Polish Black-and-White and Whitebacked bulls. For the viability, no significant differences were observed between breeds. The number of viable spermatozoa per straw in the examined semen ranged from 4.09 to 18.29 × 10⁶. This study has shown large differences in the quality of bull semen frozen between 2004 and 2010, from the collection of the National Bank of Biological Material while its quality parameters allow it to be used for insemination.