Effect of breed and season on the quality of fresh and cryopreserved ram semen

The study was conducted at the Artificial Insemination Station of the Executive Agency of Selection and Reproduction in Animal Breeding in Sofia, covering the period from June 2018 to September 2020. Ejaculates were collected from four rams of the Pleven Blackhead breed (47 ejaculates), three rams of the Assaf breed (55 ejaculates), and three rams of the Kotel sheep breed (52 ejaculates). The breed significantly influenced ejaculate volume, percentage of progressive motility, and total sperm concentration. The season of collection, on the other hand, significantly affected progressive motility in both fresh ejaculates and semen after cryopreservation. The highest mean ejaculate volume was observed in Pleven Blackhead rams, with an average of 1.108 ± 0.053 ml, while the lowest was recorded in Kotel rams, with an average of 0.718 ± 0.057 ml. The total sperm concentration in Pleven Blackhead rams averaged 2.865 ± 0.146 × 10⁹/ml, which was significantly higher compared to the Assaf rams at 2.067 ± 0.124 × 10⁹/ml and Kotel rams at 1.919 ± 0.157 × 10⁹/ml (p<0.001). Keywords: rams’ semen, semen cryopreservation, Assaf ram, local sheep breeds