This study (book) is focused on the effects of heat stress and water restriction on wool and hair cortisol, performance, behavior and immune system of sheep and dairy cows. The author measured wool cortisol in sheep as a part of his PhD dissertation for the first time in the world. The result of this work is now published in the Journal of Animal (IF =1.648) beside of 5 more SCI articles in peer-reviewed Journals at the time of graduation. However, during his Ph.D. course work, he had the opportunity to participate in further researches, which you may kindly find the resulting publications, as well as his CV or personal website. He has many years of farm working experiences beside his study in many big and industrial dairy cows farms. He has been working as a manager and animal nutritionist in Pouya dam company in Iran for years. The author is currently a post doctoral associate in Kangwon National University at the College of Animal Life Sciences in South Korea.