Cows experience heat stress when the temperature-humidity index (THI) is above 72. During heat stress, respiration rates increase, while milk production and reproduction decrease. One practice in heat stress control is to install sprinkler systems over the feed line and in the holding pen.
The objective of the sprinkler system is to wet the cow’s back, but to avoid moisture accumulation on the udder or in freestalls. Evaporative cooling occurs when the moisture is evaporated by natural or mechanical ventilation.