High levels of vitamin D are linked to better fertility and reproductive success in wild sheep, says a new study.Experts hope further studies will help determine the relevance of results for other mammals, including humans.The study published in the journal 'Scientific Reports' adds to the growing evidence that vitamin D - known as the sunshine vitamin - is associated with reproductive health.Researchers found that sheep with higher levels of vitamin D in their blood at the end of the summer went on to have more lambs in the following spring."Our study is the first to link vitamin D status and reproductive success in a wild animal population," said Richard Mellanby, head of Small Animal Medicine at the University of Edinburgh in the UK.Vitamin D is produced in the skin of sheep and other animals, including humans, after exposure to sunlight. It is also found in some foods, including certain plants. It is essential for healthy bones and teeth and has been linked to other health benefits.