**Author details**

324 Milk Production – An Up-to-Date Overview of Animal Nutrition, Management and Health

systems are available for heat-stressed cows. The intensive cooling cows with the combination of sprinklers and fans were used for improved reproductive performance. Cows were cooled in the holding area for a total 6-8 cooling periods and 4-6 cumulative h/day. Each cooling period combined cycles of sprinkling (0.5 min) and forced ventilation (4.5 min). Intensive cooling had significantly affected on decreased body temperature and allowed cows to maintain normal body temperature throughout the day [78]. In the same study, uncooled cows had high body temperature, daytime significant portion of the day and returned to normal body temperature during the late night and early morning (Figure 8).

**Figure 9.** This chart show conception rates obtained in uncooled cows during 2004-2007 and cooled

For large scale survey was carried out during a 8 yr period (2004-2011) in commercial dairy farm. The conception rate of intensively cooled cows with sprinkler and forced ventilation was significantly higher than that of uncooled cows. Conception rates obtained in intensively cooled cows in this study were similar to those obtained in that same winter in uncooled cows (Figure 9). This current finding confirmed this adverse effect of heat stress. In hot climates there is a large decrease in the fertility of dairy cows during summer months. In addition, intensively cooling cows has the potential to eliminate the decline in conception rate of dairy cows under tropical conditions. Therefore, intensive cooling is essential in dairy cows under

The exposure of dairy cows to elevate temperatures have a variety of effects, including decreased fertility, depressed appetite, and decreased milk production, all of which contribute to the goal of decreasing the production of metabolic heat in order to maintain thermo-neutrality. This chapter showed significant advantages for the evaporative cooled

cows during 2008-2011 on commercial dairy farm in the central part of Thailand.

tropical conditions to prevent hyperthermia and its harmful effects on those cows.

**11. Summary** 

Siriwat Suadsong *Department of Obstetrics Gynaecology and Reproduction, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand* 
