Combating The Heat In Dairy Herds

By Tracey Erickson

With an impending heat wave predicted for the week of July 20th-26th with highs in the upper 80 F° and low 90 F° with predicted humidity at levels in 60-70% range we will start to incur heat stress in livestock. Dairy cattle have a comfort zone of between 41 to 68 F°. When the ambient temperature goes beyond 68 F° dry matter intakes will decrease on average 0.17 lbs for each degree above 68 F°. Producers need to be vigilant in their heat stress abatement tactics.

Even though a reduction in dry matter intake and increased water intake are indicators of heat stress, producers will see a drop in milk production and butterfat, along with increased reproductive issues such as pregnancy loss. Other heat stress indicators include: open mouth panting, increased respiration, sweating, increased amount of time standing, and changes in manure consistency.

So what can you as dairy producers do to help aid in the reduction of heat stress? What follows are some basic tips for dairy cattle heat stress reduction:

• Provide shade if cattle have access to an outside lot.
• Increase access to clean, fresh drinking water. This may involve adding extra tanks of water and checking for appropriate flow of water in drinking fountains.
• Cattle that are being exposed to a holding pen in a parlor should be cooled by a combination of air movement, water sprinkling systems, and shade.
• Make sure to use large droplets of water when sprinkling (soaking) cows as small droplets often found in misters will not allow for heat dissipation from the cow. Intermittent cycles allow time for the water to evaporate and cool the animal before the next cycle. Sprinkle cows with low pressure sprinklers over their backs away from the feed bunks. Trying to keep the udders dry in this process will help minimize the incidence of mastitis.
• Use large fans in combination with sprinklers to help cool cows and the air simultaneously.
• Adjust diets accordingly as dry matter intake decreases, utilizing higher quality forages and increasing the energy density of the diet. As diet adjustments are made care should be taken to make sure that there is enough effective fiber to maximize rumination and keep acidosis and displaced abomasums to a minimum. Adding of buffers such as sodium bicarbonate to energy dense diets also help aid in appropriate rumen function.
• Diets should contain at least 0.25 lbs. of white salt per cow per day, along with offering access to free choice salt and trace minerals.