The yak (bos grunniens) is a member of the bovine family and plays a vital role in the life of the people of the Himalayan region (China, Mongolia, India, Nepal, etc). The Himalayas is an especially harsh region with long, cold winters and sparse vegetation for most of the year. As with all bovine, nutrient availability, both quality and quantity of available foodstuffs, and current status of body reserves or degree of fat stored in the body dictate the ability of the cow to conceive during a breeding season. Even though conception rate (probability of conception at a single estrus event), is high (70+%), pregnancy rate (probability of conception at the end of a breeding season) is typically only 40%-60% in their natural environments because a high proportion of female yaks fail to have an estrus during the breeding window. Understanding the major factor reducing pregnancy rate is important to creating and implementing management protocols to improve the reproductive ability of female yaks.