Michael Metzger, Michigan State University Extension Educator
(Previously published on MSU Extension, Sheep & Goat: June 29, 2012)
Extreme heat is stressful to livestock, as well as people. High temperatures are even more problematic in states like Michigan, because high temperatures are also often accompanied by high humidity. The heat index (temperature plus humidity) is a more accurate measure of heat stress than temperature alone.
Some livestock tolerate heat better than others. Sheep and goats tend to be less susceptible to heat stress than swine, cattle, llamas, and alpacas. However, goats tend to tolerate heat better than sheep. Goats with loose skin and floppy ears may be more heat tolerant than other goats. Angora goats have a decreased ability to respond to heat stress as compared to sheep and other breeds of goats.
Wool protects sheep from extreme heat as well as extreme cold. Research shows that sheep with a one-inch fleece are more comfortable than sheep with less wool, as wool fibers dissipate heat more rapidly. Woolly and hairy animals should be sheared prior to the onset of hot weather. Spring shearing allows sheep to have adequate wool growth to keep them cool in the summer (and avoid sun burning) and a full wool coat in the winter to keep them warm. Sheep and goats should not be sheared in extreme heat.
Plenty of clean, cool and fresh water is paramount to preventing heat stress in livestock. During periods of extended heat and humidity, it may be necessary to provide extra water and clean and change waterers more often. On average, a sheep or goat will drink one to two gallons of water per day. This amount will increase on hot days.
Access to shade is another important aspect of managing livestock during hot weather. Livestock shelters do not need to be complicated or elaborate. Simple shade structures can be constructed from shade cloth, mesh fabric, tarps, canvas or sheet metal. Mature trees provide excellent shade (and shelter) and are usually the least-cost alternative. While there is disagreement as to whether grazing livestock require shade, some studies show the benefits to shade.