When's the Best Time to Inseminate a Cow?

What makes a cow's reproductive system tick? Researchers at the Agricultural Research Service think they have a tiny answer to this big question.

For the best chance at successful pregnancy, it seems that hair-like structures in a cow's ovaries, called follicles, must reach full maturity before releasing an egg.

This is an important finding for livestock breeders, who often inject a hormone in cows to kick start ovulation before artificial insemination. The study suggests that if the hormone is injected too early - before follicle maturation - the pregnancy success rate drops.

The next step in this research, led by reproductive physiologist Tom Geary, is a bit trickier - figuring out the hormonal cues that bring the follicle to maturity.

Geary believes that low estrogen levels may be leading to partially developed follicles. He is investigating if giving cows extra estrogen will help mature the follicle. If it does, this could lead to higher success rates using artificial insemination methods.

These findings were recently published in the Proceedings of the National Academy of Sciences.