Question

Time of ovulation in mare is

• A. 1‐2 days before end of estrus
• B. 10‐15 hours after end of estrus
• C. 30‐36 hours after onset of estrus
• D. 12‐24 hours before end of estrus

Hint:

Because mares ovulate before the end of estrus, they are typically bred or inseminated every 48 hours starting on the second or third day of heat until ovulation is confirmed via ultrasound.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
The estrous cycle of the mare is characterized by a relatively long estrus (heat) period, typically lasting 5 to 7 days.
To ensure successful fertilization, artificial insemination or natural breeding must be timed relative to the moment of ovulation.

Step 2: Detailed Explanation:
Unlike cows (which ovulate after estrus ends) or small ruminants, the mare ovulates while still showing signs of behavioral estrus.
Specifically, ovulation occurs approximately 24 to 48 hours (1 to 2 days) before the end of estrus.
After ovulation, progesterone levels rise rapidly, causing the mare to go out of heat within 24 to 48 hours.
Because the exact duration of estrus is variable, predicting the exact time of ovulation can be challenging.
Veterinarians use serial transrectal ultrasonography to monitor follicle development; breeding is typically timed when the pre-ovulatory follicle reaches \(35\text{ mm}\) to \(45\text{ mm}\) in diameter and begins to soften.

Step 3: Final Answer:
The time of ovulation in the mare is 1 to 2 days before the end of estrus.