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Dairy Today Healthline

Hot Summer Weather Can Lead to Increased Lameness

Jun 02, 2014

Follow these guidelines to manage heat stress in your dairy herd.

By Dr. Jeff DeFrain, Dairy Research Nutritionist, Zinpro Corporation

Hot weather may not be the first thing that comes to mind when considering causes of lameness in dairy cattle, but it is common to see an increase in the rate of new claw horn lesions in cows at the end of the summer. This increase is most often driven by changes in eating and resting behavior and the subsequent increase in the risk of sub-acute ruminal acidosis (SARA).

Dairy cows begin to show signs of heat stress when the U.S.-based Temperature Humidity Indexa (Figure 1) nears approximately 68°F (20°C), which is well below the point where humans perceive heat stress. At this point, cows may show an elevated respiratory rate and body temperature, decreased feed intake and reduced milk production and reproductive performance. Cows in severe heat stress will begin open-mouth breathing (also called thermal panting). Thermal panting leads to respiratory alkalosis and the subsequent onset of metabolic acidosis.

There are a number of tools and techniques that can be used to manage heat stress on the dairy. By keeping dairy cows as comfortable as possible during times of heat stress, it is possible to minimize loss of milk and reproduction performance, minimize the increase in standing times and associated increase in new claw lesions, and maintain calf birth weights.

Ensure Cows Have Adequate Access to Water