Infrastructure
Dairy yard
Sprinklers and fans
Every dairy yard in Australia should be fitted with
sprinklers.
Sprinklers encourage heat loss through evaporative
cooling. Sprinkling cows before milking can lower
breathing rates and increase milk yields.
If cows are cool when leaving the dairy in the afternoon,
they eat more overnight.
While the production benefits are real, most farmers
nominate the reduction in flies as one of the best thing
about using sprinklers in the yard!
Priorities for cooling cows
1. Use shade first
Minimise heat gain – block solar
radiation
2. Use sprinklers and fans
Maximise heat loss – encourage
evaporative cooling
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Dairy yard sprinklers
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.
Sprinklers can be used to wet cows too so they can
off-load heat via evaporation. A small amount of heat is
also off-loaded via conduction from hoof contact with
the cooler concrete surface.
Strengths:
- 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.
Limitations:
- 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.
Spray curtains
Spray curtains are another cheap cow cooling option
that has the added benefit of keeping flies out of the
dairy – appreciated by both cows and people!
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.
Comments from the experts
The spray curtain is a cheap and effective
complement to any dairy yard sprinkler system.
It not only helps keep the dairy shed cool for
cows and milkers, 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.
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Fans
Increasing airflow from 0 m/sec to 1 m/sec increases
heat loss from a wet cow three-fold.
Fans can therefore be a useful complement to
sprinklers, especially on warm to hot days when there is
little or no wind.
Fans can also be useful in the dairy shed in conjunction
with a spray curtain, as in the example shown.
Fans only help cool cows when:
- the air temperature is lower than the cow’s body
temperature (39°C)
- the surface of the cow is wet.
In a dairy yard, fans should be mounted above
sprinklers so they remain dry and tilted 20-30° down
from vertical so that they blow down to the floor,
between and underneath cows. If fans are aimed too
high, their effectiveness will be reduced.
They are usually placed in a row with their back to the
prevailing wind, and not blowing into the dairy.
Fans range in cost from about $550 to $2,000 each,
depending on their design and capacity.
Check the efficiency rating of the fans and buy the most
efficient. Only use fans with sealed motors.
Fans in a covered dairy yard tilted
correctly
to direct airflow downwards to the floor.
A large industrial fan can be used in
conjunction with the
spray curtain to keep air circulating in the dairy
shed.
Keys to success
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
- AIM FOR a
high-volume
sprinkler with
medium-to-large droplets – 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.
- COW SHOULD not be
packed
too
tightly – sufficient air movement is needed to
allow evaporative cooling to work. Poor
ventilation results in high humidity and health
problems.
- SPRINKLERS POSITIONED
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.
- IF COWS' teats do
get wet
then either
allow time to dry, or dry them with a paper
towel before putting cups on.
- AVOID 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
- ENSURE ADEQUATE
number of
correctly spaced fans of suitable airflow
capacity for the area.
- ORIENTATE TO work
with
the prevailing
winds.
- TILT 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
‘wear and tear’.
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