Quality of Raw and of Cold-Stored Semen in Icelandic Stallions

The aim of the present study was to evaluate the quality of raw and cooled semen in Icelandic stallions. Experiments were performed using seven stallions aged between 3 and 19 years. From each stallion, six ejaculates were collected, and semen quality was determined. Thereafter, the semen was split into eight equal parts and processed with and without centrifugation using the extenders INRA 82-egg yolk, INRA 96, GENT, and Equi-Pro to a final concentration of 30 × 106 sperm/mL. The extended semen was then cooled in an Equitainer, where it was stored for 24 hours, and subsequently refrigerated for another 24 hours at 5°C. Immediately after dilution as well as after 24 and 48 hours storage, sperm motility was analyzed using computer-assisted sperm analyzer, and viability was assessed after dual DNA staining with SYBR-14 in combination with propidium iodide. The results show that the stallion had a significant (P < .05) influence on all variables evaluated in raw semen, and mean (±SEM) values of 43.4 ± 4.3 mL for the volume, 193.0 ± 17.0 × 106 sperm/mL for the concentration, 6.7 ± 0.5 × 109 for total sperm and 73.5 ± 2.1% for total sperm motility, 48.7 ± 2.0% for progressive motility, and 65.3 ± 2.0% for rapid cells were measured. In the cold-stored semen, all variables were significantly (P < .05) influenced by the stallion, extender, and storage time (48 hours). Except for Equi-Pro, all extenders examined were suitable for cooled semen preservation. For storage of more than 24 hours, centrifugation and removal of the seminal plasma were advantageous for all extenders with the exception of Equi-Pro.