Vitamin D is a boon to the fertility of wild animals

EDINBURGH, Scotland, Jan. 13 (UPI) -- Vitamin D is called the sunshine vitamin because its most efficiently absorbed by taking in the sun's rays. A new study suggests wild sheep who get a sufficient dose of the vitamin boast a healthier reproductive system.

Scientists at the University of Edinburgh in Scotland tracked levels of a vitamin D biomarker in Soay sheep found on the Hebridean island of St. Kilda. Researchers found that sheep with higher levels of vitamin D at the end of the summer birthed more lambs come spring -- the more vitamin D, the more fertile the sheep.

Previous lab studies have linked vitamin D to reproductive health of animals and humans, but this is the first time the connection has been discovered in the wild.

The latest findings, published in the journal Scientific Reports, are part of a larger effort to study Soay sheep. The unmanaged population of sheep has lived wild on the island for thousands of years.

"Our study is the first to link vitamin D status and reproductive success in a wild animal population," study author Richard Mellanby, a veterinary scientist at Edinburgh, said in a press release.

"Examining the non-skeletal health benefits of vitamin D in humans is challenging because people are exposed to different amounts of sunlight each day," Mellanby added. "Studying the relationship between skin and dietary sources of vitamin D -- and long term health outcomes -- is more straightforward in sheep living on a small island."

In humans, proper vitamin D levels play important role in maintaining bone, muscle and immune health, but evidence of the benefits of supplementation are scant.