Infrastructure
Feedpad
Case Study: Freestall shed evaporative cooling system
Farmer’s name: Michael
Facts about this system:
- Designed by: US agricultural engineer
- Built by: Contractors and family
Other cooling infrastructure on this farm:
- Solid-roofed dairy yard with fans and sprinklers
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Background
This large herd operation uses a Total Mixed Ration (TMR) feeding
system and has covered freestalls and dairy yard that provide
year-round shade and shelter. Fans and sprinklers complement the shade,
providing high levels of evaporative cooling in hot conditions. The
whole operation has been dubbed the ‘Cow Hilton’!
The fully roofed facility and cooling infrastructure allows the
property to artificially control the climate, and subsequently optimise
cow comfort and production. The farmer reports that the investment in
this infrastructure has reduced the impact of climate variation on milk
production.
The fans in the freestalls (and dairy) are:
- orientated to work with the prevailing winds
- positioned above feed alleys about every 6 m; in the stalls –
every 12 m
- pitched down towards the ground, so that they force air between
and underneath the cows to enhance whole body cooling
- operated on a temperature threshold to reduce unnecessary power
use and machine ‘wear and tear’
- set to come on above 21°C full time.
Fans set 2.3 m above cows, angled
down. All fans push air from
west to east with the prevailing wind.
Side view of the fan.
Two types of fans are used – ‘old’ fans are used in the feed alleys
and the stalls have ‘new’ ones installed.
- Old fans have 900 mm blades and move air at the rate of 285
m3/minute with a 0.45 kW motor.
- New fans have bigger 1300 mm blades and move air at the rate of
840 m3/minute with a 1 kW motor.
- Estimated cost: $65/hour to run 60 fans in one freestall (1,000
cows).
- The fans are from Fanquip.
Sprinklers mounted above the head
stanchions in a freestall barn.
Droplet size can be adjusted.
Sprinklers spraying water on cows in
the feed alley.
Sprinklers are located in the freestalls (and dairy) and are
operated based on several environmental triggers or temperature
thresholds, as well as a timed on/off cycle. This reduces operating
costs and system ‘wear and tear’.
- Sprinklers can be adjusted to alter the droplet sizes depending
on the climatic conditions.
- Sprinklers in the freestalls are 1.7 m above flooring.
- Sprinklers are spaced 3 m apart above the feed alleys, so all
feed alleys can be wetted when operated.
- Spray pattern is about 1-1.5 m back from sprinkler.
Michael’s comment
Farmers need to do their own research, look carefully at sheds
here
and overseas, and use an engineer with experience in designing these
systems.
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The sprinkler on/off cycle in the freestall area operates in the
following way:
- at 21°C a two-minute on; 13-minute off cycle
- above 25°C reduce the off cycle by 20% for every 1°C
above 25°C
- at 35°C they are on for two minutes; off for three minutes.
Water use in the freestalls (including drinking water and
sprinkling):
- 140 litres/cow/day in summer
- 80 litres/cow/day in winter.
Comments from the experts
This property is an excellent example of an evaporative
cooling
system incorporating fans and sprinklers that complements a covered
(roofed) freestall or feedpad. It provides a high level of control over
climatic conditions, and optimises cow comfort and production.
The sprinklers in the freestall shed:
- can be adjusted to alter droplet size to suit the conditions
- are operated on several environmental triggers (temperature
thresholds) as well as a timed on/off cycle
- are well spaced so that all the alley ways can be wetted
when
operated.
The fans in the freestall shed:
- are orientated to work with the prevailing winds
- are pitched down towards the ground so they force air
around and
under the cows to enhance whole body cooling
- are operated on a temperature threshold to reduce
unnecessary
power use and machine ‘wear and tear’.
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