Current Progressive Dairy digital edition

0709PD: Little details with big effects on cow cooling

Beverly Cox Published on 24 April 2009

As we move into the hottest time of the year, it is important to reevaluate the effectiveness of your cooling system. Research from the University of Florida has shown 15 to 22 percent reductions in milk yield from summer heat stress as well as poor reproductive efficiency.

Preventing, or at least limiting, the negative effects of summer heat on milk production, reproductive efficiency and udder health requires sufficient cow cooling mechanisms.



Most cooling systems include fans or a combination of fans and sprinklers. Installing these systems is a good first step, but proper maintenance and setting selection is necessary to achieve adequate heat abatement. Maximal fan performance requires routine cleaning of all fan parts and accessories.

Wind speed generated by a fan should always be at least five miles per hour directly underneath the next fan. Speeds less than this indicate inefficiencies in fan operation, possibly due to dirt buildup. Accumulation of as little as an eighth-inch of dirt on fan blades has been shown to reduce fan efficiency by 40 percent.

Fans should be cleaned at least every six months, with greater frequency during the summer months when use is greatest. A vacuum cleaner or stiff-bristled nylon brush can be used for cleaning; a power washer can be used only if the fan motor is totally enclosed. Fan motors should also be lubricated annually to prolong fan life and maximize efficiency.

Electricity should always be shut off and the fan disconnected from the power source prior to any maintenance or repairs.

Thermostat and cycle settings are also critical to the effectiveness of any cooling system. Sprinkler and fan systems should be set to operate when temperatures reach 70 to 75°F. Sprinkler cycles should run from one-half to three minutes using 0.03 gallons of water per square foot each cycle. Cycle length should be selected to soak the cow’s back, but not allow water to reach the udder. PD


—From Virginia Tech Dairy Pipeline, August 2007

Beverly Cox
Extension Agent
Virginia Tech