Heat stress has reducing effects on the productivity and reproductive efficiency of farm animals. It causes infertility and represents a major source of economic loss. In response to heat stress, managers can attempt a variety of approaches to improve reproduction.Chromium- as an essential mineral- has important role in metabolism and reduction of the negative effects of stress. In ruminants, supplementation of Chromium is recommended during heat stress periods, early lactation, infection, etc.Selenium-E, is an essential part of the antioxidant defense system, plays an important role in the growth and health of humans and livestock through its participation in several important enzymes and enzyme reactions. Selenium-E deficiency has been related to reproductive failures in ruminants.