**1. Introduction**

Arid and semi-arid zones account for one third of the earth's surface land area and cover most parts of the developing nations in the world including Latin America, Africa, and parts of India and South East Asia. Nevertheless, these ecosystems are not exclusive of developing countries because they also exist in developed nations such as United States of America, Spain, Australia, and Israel, among others. Arid zones are characterized by excessive heat loads and an insufficient and erratic pattern of precipitation. Also, actual evapotranspiration equals rainfall and recharge of groundwater is relatively infrequent. In general, summers are very hot and intense, but winters have commonly cold weather. In many countries with arid zones, high environmental temperatures during summer seasons may last up to 6 months, with average temperatures over 30°C. This is important because approximately one third of the cattle population in the world is located in arid zones, and according to IPCC predictions, the global average surface temperature may increase between 1.8 and 4°C by year 2100 (IPCC, 2007). The negative effects of global warming will be manifest in animal agriculture of both developed and developing countries, but the pressure will be greater on developing countries because of their deficiency of resources, their lack of veterinary and extension services, and their limitations on research technology development (FAO, 2007).

One of the chief problems facing dairy producers located in arid regions is thermal stress. In temperatures above 28°C, even without humid conditions, lactating cows show evidence of hyperthermia and emerges a condition called heat stress, so that the events feed intake, milk yield, milk fat and protein production, as well as fertility rate are reduced. Meanwhile, body temperature and respiration rate show a significant increased (West, 2003).

There are a number of options to assist in minimizing the negative effects of heat stress on dairy cows. Some of these options are feeding management, housing and facilities

© 2012 Avendaño-Reyes, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2012 Avendaño-Reyes, licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

adjustments, and selection of tolerant breeds. Rations should be adjusted to increase energy and protein intake while maintaining rumen and cow health. The purpose is to increase the quantity of grain fed and decreased the quantity of forage in the ration. Also, environmental modifications that help to alleviate heat stress problems are structure orientation, structure ventilation, use of shades, and use of cooling systems in different sections of the dairy farm. Evaporative cooling means a combination of wetting and forced ventilation drying the cow's coat to maximize the cooling effect. Milking parlors with adequate holding pens can employ the use of subsequent sprinkling and forced air in the pens. In dairies with adequate drainage and housing, evaporative cooling can be provided above the feed bunks in addition to or instead of in the holding pen (Armstrong, 1994).

Therefore to reduce heat stress on dairy cattle it is required a multi-disciplinary approach and should include nutrition, environmental modifications, and management practices. This chapter will focus on these strategies with special reference to arid zones.
