Watch for heat stress in dairy cattle

Heat stress in dairy cattle is one of the leading causes of decreased production and fertility during summer months. These losses are apparent in the decreased amount of milk shipped, increased days open and decreased breedings per conception. Some heat stress is unavoidable but effects can be minimized if certain management practices are followed.

The ideal temperature range for dairy cattle is between 25 degrees and 65 degrees Fahrenheit. Once the temperature reaches 80 degrees cattle reduce feed intake, which has a negative impact on production. At 90 degrees or above, one can usually notice a dramatic decrease in milk production ranging from 3 to 20 percent. Humidity also plays a significant part in heat stress. A temperature of 100 degrees and 20 percent humidity is the range in which you begin serious measures to ease the stress on cattle.

Signs of heat stress:

• Seeking out shade
• Increased water intake
• Reduced feed intake
• Standing rather than lying down
• Increased respiratory rate
• Increased body temperature
• Increased salvation
• Reduced milk production
• Reduced conception rates

Ways to help the cattle:

• Ensure the cattle have adequate access to good quality, cool drinking water
• Allow the cows to take their time when moving them to and from the barn..
• Slightly modify milking times so that milking is completed early in the morning before it gets too hot and, on very hot days, holding milking back to cooler parts of the evening.
• Avoid excessive crowding.
• Ensure there is good air flow by installing fans, opening the sides of the barn, and making sure there is enough shade if cattle are outside.
• Install misters or sprinkler systems.

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