Effects of a long-day light programme on the motility and membrane integrity of cooled-stored and cyropreserved semen in Shetland pony stallions.

The research investigates whether artificial long days can enhance the quality of cooled-stored and cryopreserved semen in Shetland stallions. The findings indicate that the extended light exposure has a potentially beneficial impact, which is reflected by improved motility and membrane integrity of the spermatozoa.

Research Methodology

• The study involved a treatment group (AL, n=8) and a control group (CON, n=7) of Shetland stallions.
• The treatment group was exposed to 16 hours of light and 8 hours of darkness from December 15 to March 20, creating artificially long days. Conversely, the control group lived under a natural light-dark cycle.
• Semen was collected once per week for analysis and processed for chilled storage and cryopreservation once per month.

Measurements and Results

• The researchers measured total and progressive motility (i.e., the ability of sperm to move properly towards an egg) and the percentage of membrane intact spermatozoa at 24, 48, and 72 hours of cooled-storage. They also took measurements after the freezing-thawing process.
• They found an overall decrease in total and progressive motility and membrane integrity over 72 hours in both groups, but the decrease was more pronounced in the control group.
• However, they noticed that the differences between the group’s results reduced as the observation period progressed from January to July.

Conclusions

• Neither total and progressive motility nor the percentage of membrane-intact and morphologically defective spermatozoa in the frozen-thawed semen varied significantly between the groups or over different months.
• The study demonstrated a reduction in cooled-stored semen’s motility in January, but it increased when stallions were exposed to artificial long days for at least 30 days.
• These findings could indicate that modifying light exposure could enhance the quality and longevity of cooled-stored and cryopreserved semen in stallions. This aspect opens possibilities for optimising equine reproduction practices and management.