Infertility during heat stress is primarily caused
by elevated body temperature within the dairy cow.
Cooling dairy cows during heat stress should,
therefore, improve conception rates. A variety of
cooling systems are available for heat-stressed
dairy cows. Perhaps the most widely used system
is a combination of water sprinklers and fans.
Sprinkling cows with water and subsequently
blowing air over the cow with a fan causes
evaporative cooling. The evaporative cooling
decreases body temperature. Several investigators
have tested the effects of cooling on reproduction.
In general cooling cows will improve reproductive
performance. However, cows cooled in the
summer never achieve the same rates of
conception when compared to normal cows in the
winter. Therefore, cooling can only partially
alleviate the effects of heat stress on reproduction.