Sprinklers & Fans
Sprinklers encourage heat loss through evaporative cooling and are an effective method of cooling a large number of cows quickly.
Dairy yard sprinklers assist cooling in a few different ways. Sprinkling cows before milking can lower breathing rates and increase milk yields. If cows are cool when leaving the dairy in the afternoon they will eat more overnight.
Sprinkled concrete loses heat via evaporation and conduction through contact with the cooler water. This reduces its ability to re-radiate heat to the cows standing on its surface. A small amount of heat is also off-loaded via conduction from hoof contact with the cooler concrete surface.
Sprinklers can also be used to wet cows so they can off-load heat via evaporation with the assistance of fans.
Dairy Yard Sprinklers
Sprinkler systems are relatively easy to install and can be built from irrigation or garden sprinklers and poly pipe.
Droplets must be medium large to allow water to penetrate the hair coat and wet the cow's skin.
Sprinklers should be spaced at intervals of 1.5 to 2.0 times their wetted radius so there is a slight overlap of wetted areas.
Piping must suit the length and area to be sprinkled, the number of sprinklers and their flow rate. Piping can be PVC or polythene and any exposed pipe should be painted white to keep water cool. The ideal water temperature is 15-20C.
For more information go to Design Considerations for Sprinklers.
Spray curtains are a relatively cheap cooling option that has the added benefit of keeping flies out of the dairy.
Spray curtains can be used in dairy yards but are normally attached to the underside of the dairy shed roof between the yard and the platform.
The example shown was constructed for less than $100 using 19 mm black polyethylene attached to the roof with garden sprinkler sprays inserted into the pipe every metre. It is about 2.5 m above the cows' feet level.
The sprinklers generate a semi-circle spray pattern that is directed towards the yard side of the shed.
Polyethylene pipe attached to the dairy shed roof for the spray curtain.
Spray curtain water supply and filter.
Spray curtain in operation.
- Low capital outlay.
- Can be easily fitted to any dairy yard (or feedpad) with a concrete floor.
- Effective method of cooling a large number of cows quickly.
- If droplet size is too small cooling will not be effective.
- Use in high humidity conditions actually increases heat load on cows.
- Without adequate air movement, cooling using sprinklers is not effective.
- Need access to a reliable water supply.
The spray curtain not only keeps the dairy shed cool for cows and milkers, but it also reduces fly numbers in the dairy by washing flies off cows on entry and providing a wall of mist that prevents flies from entering the shed.
Remember that for evaporative cooling to be effective, the cows' skin needs to be wet, but not so wet that water dribbles down the udder.
Sprinklers in dairy yards
- AIM FOR MEDIUM-SIZE DROPLETS on a high-volume sprinkler to avoid a fine mist.
- COVER THE ENTIRE DAIRY YARD, so that all cows are wet in the first 10 minutes.
- CONSERVE WATER by installing a timer and running sprinklers on an on/off cycle. For example sprinkle cow for 1-3 minutes every 15 minutes.
- DON'T PACK COWS TOO TIGHTLY sufficient air movement is needed to allow evaporative cooling to work. Poor ventilation results in high humidity and health problems.
- POSITION SPRINKLERS along the sides of a dairy yard need to be mounted high enough to project water up and over cows, so it falls from above (ideally 2 m). This will minimise wetting of udders and the risk of mastitis. It will also prevent water being thrown directly into cows' ears.
- DRY COWS' TEATS if they get wet & allow time to dry, or dry them with a paper towel before putting cups on.
- AVOID WETTING AFTER MILKING - wetting cows immediately after milking to prevent teat disinfectant from being replaced with contaminated water while teat orifices are still open.
- PRE-WET THE DAIRY YARD by hosing, flood washing or sprinkling for the hour before cows arrive for afternoon milking. This helps dissipate the heat stored in the concrete.
Fans & sprinklers in dairy yards
Fans are a useful complement to sprinklers , especially on days when there is little of no wind. fans only help cool cows when:
- the air temperature is lower than the cows body temperature (39C).
- the surface of the cow is wet.
For more information go to Design considerations for fans.
Keys to success
In a dairy yard, fans should be mounted above sprinklers.
- SPACE OUT FANS EVENLY number of correctly spaced fans of suitable airflow capacity for the area.
- ORIENTATE FANS to work with the prevailing winds.
- MOUNT FANS ABOVE SPRINKLERS.
- TILT FAN DOWN so they blow air between and underneath cows to enhance whole body cooling.
- OPERATE ON a temperature threshold to reduce unnecessary power use, and machine âwear and tearâ.