Like death and taxes, dairy cows can’t avoid hot weather. Once the total heat index (THI) hits 68, cows begin to lose production. But with the right management focus, you can help cows get through heat stress with minimal adverse health events and lost production. Just focus on three key areas. 

Put cows in a cooling cycle.

Heat stress happens when the cow’s heat load is greater than her capacity to lose heat. When cows are hot they pant and sweat, but neither is nearly effective enough to expel the large amounts of heat created by cows. The formula to alleviate heat stress is simple: soak, dry, repeat.

Evaporative cooling is the most effective method for expelling heat from the cow. In this process cows are soaked with water, then air movement over the cow creates an evaporative effect that pulls heat from the body, increasing cows’ natural evaporation rate to improve cooling.  

In the past, cows have stood for long periods of time under misters to get cool. That method has improved to a process that includes large droplets of water sprayed over the entire back of the cow for a brief period of time, long enough for water to get under the cow’s hair and to the skin. 

It’s important to create a cooling cycle that includes a soaking period followed with drying time. Create enough water volume to cover the cow in 30 seconds or less, timing it so about 80% of the cow is dry before soaking again. To achieve this level of dryness in a short amount of time takes good air flow, and air flow takes fans.

The more fans in the barn creates more consistent air flow on top of cows with fewer dead spots. Use fans with good spread and throw to get the best coverage and best return on evaporative cooling benefits. 

Technology is available to help make the soaking process efficient. Sensors can recognize if a cow is in a lockup and turn off the nozzle if no cow is present. Controllers can break the barn into quadrants and manage soaker times long enough to get cows soaked, then turn off. They can be set so they turn off when no cows are present, such as when a pen is in the holding area. 

One common area where heat stress affects cows is the holding area. Cows can quickly spike high temperatures while standing packed into tight areas during high THI periods. Soakers and fans play an essential role in ensuring both cooling and adequate ventilation in these close quarters.

Supply cool, clear water.

Evaporative cooling can help remove heat from cows and alleviate heat stress, but providing large amounts of cool, clear water is key. Here are a few points to consider when providing water to cows:

• Provide ample and readily available access to water troughs. Create 5 linear inches of trough space per cow, and ensure cows are never more than 50 feet from a water source.
• Keep troughs clean, but don’t over chlorinate. Cows are creatures of smell and will avoid water troughs with a strong chlorine smell.
• Set the proper float level to allow for maximum fill.

One of the best things you can do to provide cows with an ample supply of water when they want it most is to install a water source in the parlor return lane. Cows will consume 30 to 50% of their daily water needs within an hour after milking, so nearly every cow will stop to drink when walking away from the parlor. The process will also improve feed intake when she gets back to the feed bunk.

Replenish lost nutrients.

When hot cows pant, sweat and urinate they lose valuable nutrients. One of those key nutrients lost is potassium. When cows are hot, the amount of potassium lost can increase five-fold. To offset this loss increase dietary potassium through DCAD Plus™ to 1.8% while maintaining the K:Mg ratio at 4:1 on a dry matter basis.

Likewise, when respiration increases more carbon dioxide is released, lowering the blood buffering capacity. Increase levels of SQ-810™ or ARM & HAMMER™ sodium bicarbonate a full pound per cow per day. 

A good measure of buffering capacity is the dietary cation-anion balance. In pre-fresh cows, DCAD levels need to be significantly negative to prepare the cow for calving. Conversely, DCAD levels need to be considerably positive, in the +35 to +45 area, to maximize blood buffering. 

Finally, increase the energy density of the ration through products like MEGALAC® and ESSENTIOM™ by providing 1/2 to 1/4 pounds per cow per day.

The impact of heat stress on cow health and performance can be devastating, but the solution can be simple. Just minimize heat gain and maximize heat loss. Do this by providing the right management to maximize evaporative cooling; provide ample amounts of cool, clear water; and provide the right nutrition to replenish lost nutrients. 

Contact your ARM & HAMMER representative to discuss applying cow cooling strategies on your farm.