Combat Heat Stress

by Dr. Armon Hetzel, ANIMART ProHealth Veterinarian

Heat stress in lactating dairy cattle is a common issue on farms during summer months. Cows are considered to be in their thermal comfort zone between 40 °F and 75 °F and will start experiencing heat stress around 75°F with a relative humidity of 70% or higher.

Typical signs of heat stress include:

• Reduced dry matter intake

• Decreased milk production

• Panting

• Shallow breathing

• Lethargic behavior

While these are all signs heat stress may be a problem, it is best to take a proactive rather than reactive treatment approach.

Effective heat abatement practices include:

Access to Water and Shade

Water availability is essential for lactating dairy cows. It is the primary nutrient needed to survive and produce milk, as it accounts for 85% of milk’s content. The need for water increases significantly during warmer temperatures as cows’ water intake may increase up to 50% once the temperature/ humidity index reaches 80%. Water should be readily available to cows soon after exiting the parlor. Shade structures, natural, permanent or moveable should be located near water and over feed mangers.

Fans and Sprinklers

The use of sprinkler systems in housing and holding areas can be very effective in heat abatement. Sprinklers work in reducing heat through evaporative cooling. It is important to use sprinklers with proper ventilation and air flow, as sprinklers used in humid environments can actually trap heat in the cow.

There are many different systems of air flow and ventilation that can be used to fit with different housing needs. Tunnel ventilation, circulation fans or sidewall fans can all be effective.

Diet Adjustment

Heat stress’ biggest impact to a producer’s bottom line is decreased milk production due to reduced dry matter intake. Decreasing intake can reduce the amount of heat produced. Every pound of decreased dry matter intake will result in a two pound loss of milk production during times of heat stress.

High quality forages digest faster while producing less heat, so increasing the energy density of the ration may be an option. ANIMART carries feed additives including electrolytes such as Bovine Bluelite and direct-fed microbials such as Bovamine, which can increase feed intake helping to reduce the negative effects of heat stress. Make sure to consult a nutritionist before making ration changes.

It is important to remember dry cows, heifers and calves needs during warm temperatures as well. Adequate shade, ventilation and availability to water are all effective heat abatement practices.

For more information on how ANIMART can aid in lessening the severity of heat stress in dairy cattle, consult a trusted ANIMART representative.