Management and fertility of mares bred with frozen semen.

The research article focuses on the factors impacting the pregnancy rates when breeding mares with frozen semen. The study details the importance of semen quality, mare status, management practices during estrus, along with the critical role of precise ovulation timing and of post-breeding examinations.

Semen Quality and Mare Selection

• Quality of the frozen semen used is a top factor affecting pregnancy rates. If semen quality falls below optimal, the correct selection of the mare and proper reproductive management become vital in determining success.
• Old maiden mares and mares with reproductive challenges should be checked regularly for normal cyclicity. All except young maiden mares should undergo a uterine culture and cytology. Mares that show positive bacterial cultures and cytologies should receive the proper antibiotic treatment for at least three consecutive estrus days.

Timing Ovulation

• One of the keys to success with frozen semen is accurately timing the ovulation to minimize the time between breeding and ovulation. The frozen semen undergoes “capacitation-like” changes during freezing and thawing processes, which can shorten sperm longevity. Hence, breeding closer to the ovulation process can potentially increase the chances of fertility.
• The research suggests the use of ovulation-inducing agents like human chorionic gonadotropin (hCG) or the GnRH analogue, deslorelin. Most hCG treated mares ovulate 48h post-treatment, whereas most deslorelin treated mares ovulate within 36-42h post-treatment.

The Role of Breeding Cycle

• The study notes an improvement in pregnancy rates for mares bred more than once in one breeding cycle, compared to those bred just once pre- or post-ovulation. This is a slight but consistent rise.
• Research indicates that breeding close to the uterotubal junction increases sperm count in the oviduct, thus increasing pregnancy chances.

Post-Breeding Examinations

• Post-breeding examinations can pinpoint ovulation time and identify uterine fluid accumulations, allowing for timely post-breeding treatments.
• Generally, the pregnancy rates for mares bred with frozen semen range between 30 and 40%. This figure can greatly vary depending on the sires. Stallion and mare statuses are crucial in determining frozen semen insemination success.

The Importance of Proper Communication and Dedication

• Effective communication with the client is an integral part of a successful frozen semen program. It requires careful selection of both stallions and mares.
• Dedication and commitment from the mare owner and inseminator play a key role in achieving high pregnancy rates.