However, there are some important factors to consider:
* Breed: Some breeds of cows are known for having twins or even triplets, though this is less common.
* Management practices: Farmers can influence the number of calves a cow has through breeding practices, such as artificial insemination and controlled breeding seasons.
* Health: A cow's health and age can also impact how many calves she has.
So, while one calf per year is the most common scenario, there is some variation depending on the individual cow and the factors mentioned above.