Does the ewe or ram determine twins?

Answered by Willian Lymon

The question of whether the ewe or the ram determines twins in sheep reproduction is an interesting one. To answer this, we need to understand a bit about the reproductive biology of sheep.

In sheep, both the ram and the ewe play important roles in the process of reproduction. Rams are known for producing large quantities of sperm, numbering in the hundreds of thousands. This is because their primary goal is to successfully fertilize the ewe’s eggs. The more sperm they produce, the higher the chances of successful fertilization.

However, the number of sperm produced by the ram does not directly influence the occurrence of twins or multiple births. Instead, it is the ewe’s reproductive system that determines whether she will release multiple eggs during ovulation, leading to the possibility of twins or even higher-order multiple births.

In most cases, sheep typically ovulate only a single egg during each reproductive cycle. However, there are instances when the ewe may release more than one egg, resulting in the potential for multiple pregnancies. This phenomenon is known as multiple ovulation.

The occurrence of multiple ovulation in ewes is influenced by various factors, including genetics, breed, age, nutrition, and overall health. Some breeds of sheep are more prone to multiple ovulation than others. For example, certain meat breeds, such as the Dorset, are known for their higher likelihood of producing twins or triplets.

The ewe’s hormonal balance also plays a significant role in determining the occurrence of multiple ovulation. Hormones such as follicle-stimulating hormone (FSH) and luteinizing hormone (LH) regulate the development and release of eggs from the ovaries. Imbalances in these hormones can increase the chances of multiple ovulation.

It is worth noting that while the ewe’s reproductive system determines the potential for multiple pregnancies, successful fertilization of the released eggs still depends on the ram’s sperm. The competition among the sperm to fertilize the eggs released during ovulation can be intense, and only the strongest and healthiest sperm will be able to penetrate and fertilize the eggs.

In my personal experience as a sheep farmer, I have witnessed both single and multiple pregnancies in my flock. While I have observed that certain ewes tend to have a higher likelihood of producing twins or triplets, it is ultimately up to their reproductive biology and factors beyond my control as a farmer.

To summarize, the occurrence of twins or multiple births in sheep is primarily determined by the ewe’s reproductive system and her ability to release multiple eggs during ovulation. While rams produce a large quantity of sperm, it is the ewe’s reproductive biology that ultimately determines the potential for multiple pregnancies.