July 26, 2019

Be Mindful and Take Action Against Heat Stress This Summer

Bovine Heat Stress

With summer in full swing, high temperatures are here to stay. Increasing temperatures can have a multitude of negative effects on animals that are in the sun and heat throughout the day, including dairy cows.  

Air temperature, humidity and the amount of direct sunlight impact an animal’s body temperature. As summer temperatures continue to rise, it’s critical to avoid heat stress that can lead to lameness in dairy cows.

Causes and Symptoms of Heat Stress

Cows are at increased risk of heat stress when temperatures exceed 80 degrees Fahrenheit for extended periods. High humidity and little-to-no breeze can increase the risk even more. Since summer is also the peak season for flies and pests, cows tend to group together to combat stinging and biting insects. As they gather, heat transfers from one animal to another, and the added body heat of the herd contributes to heat stress too.

Observe dairy cows frequently for signs of heat stress and take precautions when hot and humid weather is forecasted. Common signs and symptoms of heat stress include:

  • Excess Standing: During the hot summer season, a cow’s natural response to heat is to stand. Because a cow generates heat when they lie down in a stall, excessive standing, grouping and huddling of a herd are visible signs of heat stress. As heat stress progresses, cows generally stand three-to-four hours more per day than usual and refuse to lie down.
  • Increased Respiratory Rate: Since cows are unable to sweat and alleviate their body heat, labored or open-mouth breathing and panting are the animal’s way of introducing cooler air into their bodies. If a cow maintains an increased respiratory rate with excessive saliva or drooling, heat stress is likely the cause.
  • Changes in Behavior and Activity: Similar to a human’s reaction to extreme heat, cows alter their behavior to reduce stress when exposed to extreme temperatures. Like a human, when a cow experiences heat stress, its activity and energy levels decrease. If a cow appears agitated, restless and, in extreme cases, lame, heat stress may be the cause. Other changes in behavior include reduced feed intake and increased water intake.

Heat Stress and Lameness Issues

During extreme temperatures, cows stand to allow more of their surface area to disperse heat into the air. Although cows are tough, their heavy bodies cannot withstand long periods of standing.

The extra pressure from excess standing affect the integrity of the hoof and restrict the blood flow and oxygen needed to maintain healthy hooves. As a result, cows are more prone to injuries and infectious claw lesions as they put extra pressure on their hooves.

Blocking can help regardless of the injury or condition to keep milk production moving. Hoof care professionals place a rubber block on a healthy claw to elevate and restrict the affected claw. This treatment option will elevate the injured claw off the ground, and it will heal faster and alleviate pain. Rubber blocks from Bovi-Bond™ provide the necessary traction and cushion hooves need for a dairy cow to stay comfortable and avoid injury during the healing process.

Different adhesives can be used to adhere blocks on the claws to increase the cow’s comfort level. Bovi-Bond™ from Vettec is a proprietary two-part polyurethane adhesive that bonds rubber blocks to a cow’s claw. It has a fast, 30-second set time and a strong bond to keep blocks in place.

For best results, only apply the necessary amount of glue to hold the block firmly to the foot. Spreading the adhesive evenly across the block ensures the glue will dries smoothly and reduce the chance of sharp edges forming that could perforate the cow’s heel. Blocking helps make the cow more comfortable and, therefore, allows farms to maintain optimal milk production.

Managing Heat Stress

There are different tips and techniques farmers and hoof care professionals can use on dairy cows to prevent heat stress and lameness. Some examples include:

  • Maintain regular cool off periods and keep cows inactive until temperatures decline.
  • Alter milking and trimming routines to avoid additional headlock time. Mornings and nights are the best times for herd movements to minimize exposure to peak heat hours.
  • Install sprinklers, misters and barn fans for ventilation.
  • Create shade in outdoor environments to provide more comfort.
  • Provide readily-available water sources within in short walking distances.
  • Make sure the herd receives vital nutrients with continued feeding periods to maintain milk production. Discuss any adjustments to feed ratios with a nutritionist.
  • Pay extra attention to calves in the warmer months to keep them happy and healthy.

As summer temperatures increase standing time and the possible onset of heat stress, dairy farmers tend to see more cows experiencing lameness in the fall. Talk to your hoof care professional about the importance of adopting a good hoof care protocol during summer months, and the best options for your dairy environment.