Stress is a broad term, generally used in negative connotation and is described as the cumulative detrimental effect of a variety of factors on the health and performance of animals. Global climate change is expected to alter temperature, humidity, rainfall, atmospheric carbon dioxide. The dairy sector is a more susceptible to climate change and global warming where it is mostly affected by the temperature and humidity such as temperature humidity index (THI). Combined effect of high ambient temperature and high humidity results adverse effect on reproductive performance of farm animals. It is important to understand the livestock responses to environment, analyze them, in order to design modifications of nutritional and environmental management thereby improving animal comfort and performance. Reducing heat stress in livestock requires multidisciplinary approaches which emphasize housing, animal nutrition (feed formulation and feeding strategies), by biotechnology viz., by developing thermotolerant animal breeds and by improving disease control strategies and health services.