Effects of oxygen exposure and gentamicin on stallion semen stored at 5 and 15 degrees C.

This research studied the effects of oxygen exposure, temperature, and the use of the antibiotic gentamicin on the quality of stallion semen. It was found that storing semen at 5 degrees C without antibiotics had the best results while temperature and bacteria growth played a significant role in semen quality if stored at 15 degrees C.

Objective and Methodology

• This study aimed to examine the impact of storage conditions including temperature, oxygen exposure, and the application of the antibiotic gentamicin on the quality of stallion semen. The experiment focused on two temperatures: 5 and 15 degrees Celsius, and two conditions: aerobic (in the presence of oxygen) and anaerobic (without oxygen), with and without gentamicin.
• Semen samples were collected from eight fertile stallions and stored for 96 hours. They were assessed daily for motility, velocity, and viability using a Computer-Assisted Sperm Analysis (CASA) system. Bacteriological assessment was also conducted on day 2 of storage.

Findings and Interpretations

• For the first 2 days of storage, no significant differences were observed in the motility, velocity, or viability of the semen samples across the different storage conditions.
• On days 3 and 4, however, semen stored at 5 degrees C without gentamicin showed significantly better quality than semen stored at 15 degrees C without the antibiotic.
• The researchers found that bacterial growth, particularly at 15 degrees C, had a pivotal role in diminishing the quality of semen. This growth was more pronounced in samples stored without gentamin, under both aerobic and anaerobic conditions.
• Adding gentamicin to samples stored at 15 degrees C inhibited bacterial growth and, consequently, slowed down the decline in sperm quality.
• In contrast, the use of gentamicin in samples stored at 5 degrees C did not significantly impact any of the parameters analysed, suggesting that the lower storage temperature maintained better semen quality without the need for antibiotic treatment.

Concluding Thoughts

• The researchers concluded that if stallion semen is to be stored at 15 degrees Celsius, it’s beneficial to include an antibiotic like gentamicin in the extender to inhibit bacterial growth and maintain semen quality.
• However, storage at 5 degrees Celsius without the antibiotic is more effective at maintaining stallion semen quality, regardless of oxygen exposure, indicating a lower temperature is more beneficial for semen storage.