We all know that cows are sensitive to heat stress, with cumulative, negative effects that compromise both cow productivity and farm profitability. It’s important that both humidity and temperature (THI) are taken into consideration when measuring heat stress levels because humidity will affect at what temperature cows become heat stressed.

Veeneman dan
Cow Cooling Product Specialist / InBarn

In climates where humidity is high, the most effective method to cool a cow is low-pressure soaking. Soaking works on the basis of reducing the temperature of the cow through evaporative cooling. Large water droplets wet the cow’s back; the water draws the heat off the cow; and combined with airflow, the water evaporates from the cow’s body to cool her.

Sounds very simple, yet there are numerous dairy farms where soaking is not working the way it should. Here are five tips for making the most out of a soaker system for cow cooling:

1. Automation: A soaker system needs to be automated. People often forget that they have a higher tolerance to heat, and if they aren’t feeling hot, they might not think to turn on the system. Having a controller that turns the system on and off based on environmental parameters simplifies the process, freeing up your staff to do more important work.

2. Preventative approach: Whether it’s in a feed lane or parlor, it’s important to take a preventative approach to soaking.

  • In feed lanes, to prevent heat stress, soakers are typically set to turn on at 66°F to 68°F.
  • In parlors, they should turn on at 61°F to 66°F, as body temperature will increase as cows walk to the parlor and as they gather together in the holding area. This is not only to prevent heat stress, but also an undesirable microclimate of heat, stale air, moisture and pathogens that causes additional stress right before she steps onto the milking platform.

3. Run times: On/off times should be governed by temperature and humidity. The hotter the temperature, the more frequently soakers should run.

  • In lower temperatures, soakers should run in one to one and a half minute intervals (based on nozzle flow rates) every nine minutes.
  • As temperatures increase, the cycle time should be reduced to every five minutes.

4. Spray: For a soaking system to be truly effective, a number of factors must work together. Water pressure, spray radius, spray pattern, nozzle size and placement all play a part in effective soaker system design.

  • Water pressure needs to run at approximately 20 psi. The low-pressure system allows for larger droplet size, which is more effective at breaking through the cow’s hair to soak her skin.
  • If the droplets are too small, the water is unable to penetrate and will actually create an insulating layer, which will insulate the cow versus cool her down. Smaller droplets are also more susceptible to wind drift and can wet bedding and feed.
  • Spray patterns and radius will vary based on soaker location and building design. For instance, feed lanes only need a 180-degree radius, whereas holding areas require a 360-degree radius. Depending on the construction of the barn, farmers need to be aware of how far the water sprays and whether or not it’s hitting the freestalls.
  • Nozzles need to be chosen with flow rate and size in mind, and spacing is critical. Once the correct spray pattern has been determined along with water pressure, the goal should be to space nozzles as far apart as the throw radius.

Effective soaking figure

5. Enhance cooling with fans: Soaking, although effective at cooling cows on its own, isn’t nearly as effective as when fans are added.

  • The graph (Figure 1) shows that soakers without fans have the ability to drop the cow’s temperature slightly, and that the shorter the interval between soakings, the more effective the soakers are at cooling cows.
  • The more significant cooling effect was with a combination of fans and soakers, with shorter intervals between soakings being more effective at cooling cows.

Soaking is a key tool in the battle against heat stress in hot and humid climates. A well-designed soaker system as part of a complete heat abatement strategy will help you avoid many of the costly effects of heat stress, which will allow you to keep more of your hard-earned money in your pocket.  end mark

PHOTO: In climates where humidity is high, the most effective method to cool a cow is low-pressure soaking. Photo by Mike Dixon.

Dan Veeneman