Evaluation of a Proprietary Slow-Release Oxytocin Formulation on Corpus Luteum Function in Mares.

This study investigates the effectiveness of a slow-release oxytocin formulation in extending the functioning of the corpus luteum in mares. The findings suggest that this formulation, which only requires two treatments rather than the current standard of daily doses, can indeed prolong corpus luteum function.

Objective and Methodology of the Study

• The research focuses on testing a novel method to suppress estrus – the ovulatory phase of the reproductive cycle – in mares via prolonging Corpus Luteum (CL) functioning.
• The investigators developed a proprietary slow-release oxytocin formulation that could simplify and optimize the conventional daily protocol of administration and assessed it to find its impacts.
• Mares were monitored through transrectal palpation and ultrasonography to ascertain the ovulation day, and were then randomly categorized into control and slow-release oxytocin (SR-OT) treatment groups.
• The treated mares received one-milliliter doses of SR-OT (which contains 2,400 IU oxytocin) via intramuscular injection on the seventh and tenth day following ovulation.
• Jugular blood samples were collected from the mares at the beginning, then three times a week for 50 days for examining the serum progesterone concentration. This hormone, produced by the CL, could evidence the success or failure of the treatment.

Findings of the Study

• Nearly 75% of the mares that had the SR-OT treatment were found to have extended CL function. Conversely, none of the untreated control group mares had prolonged CL activity.
• Functioning is considered prolonged if the progesterone concentration in their serum remained at levels above 1.0 nanogram/milliliter continuously for at least 30 days.

Significance and Implications of the Research

• These results are particularly relevant as they validate the efficacy of the two-injection SR-OT protocol, which represents a drastic 75% reduction in treatment frequency compared to the standard daily administration from day 7-14 post-ovulation.
• It has the potential to make estrus suppression treatments more practicable through the elimination of the need for daily administration, thus improving the welfare of the mares and reducing the workload and costs of treatment.