Question

Which of the following species has seasonally polycyclic estrus cycle?

• A. Cow
• B. Sow
• C. Bitch
• D. Mare

Hint:

Keep these reproductive classifications in mind:
- Mares & Queens: Seasonally polyestrous (Long-day breeders).
- Ewes & Does: Seasonally polyestrous (Short-day breeders).
- Cows & Sows: Year-round polyestrous.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
The estrous cycle is the reproductive cycle of female mammals, regulated by gonadotropic and ovarian hormones.
Based on the frequency and seasonal patterns of these cycles, animals are classified as polyestrous, seasonally polyestrous, or monoestrous.

Step 2: Detailed Explanation:
Let us classify the estrous patterns of the listed species:
- Cow (A) and Sow (B): These species are year-round polyestrous.
They cycle continuously throughout the year at regular intervals (approximately every 21 days) regardless of the season or day length.
- Bitch (C): The female dog is monoestrous.
She typically exhibits only one or occasionally two estrous cycles per year, followed by a prolonged period of anestrus.
- Mare (D): The mare is seasonally polyestrous (specifically a long-day breeder).
Mares experience multiple, consecutive estrous cycles during a specific season of the year when day length is long (spring and summer).
As day length shortens in autumn and winter, they enter a period of reproductive inactivity (anestrus).
This adaptation ensures that offspring are born during the spring when environmental conditions are optimal for survival.

Step 3: Final Answer:
The mare is the species that has a seasonally polycyclic (polyestrous) estrus cycle.