Infrastructure
Dairy yard
Shade structures
Minimising heat gain through shade should be the first priority for
farmers hoping to keep their cows cool.
There are two main options for providing shade in the dairy yard.
The cheapest is shade cloth and if well-constructed and maintained
it can have a lifespan of at least 10 years. Solid-roofed shade
structures last much longer, but are more expensive to build.
If complemented with sprinklers and air movement at milking time,
shade provided at the dairy yard is particularly effective in cooling
cows. If the cows’ skin is wet, air movement enhances cooling. It also
allows for faster milk let down and more incentive for the herd to walk
to the dairy.
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
|
Shade cloth structures
Shade cloth minimises solar radiation – the cows can voluntarily
seek shade to off-load heat via evaporation.
Strengths:
- Shade cloth is porous, so heat evaporated from cows can vent
through it.
- The small amount of radiation that penetrates through the shade
cloth ensures the concrete surface regularly dries out, which prevents
mould / bacteria from establishing on the concrete and reduces risk of
the cows slipping.
- Can be manufactured off-site then installed in a day.
- Can be removed in cooler months.
- In most council areas no planning permit is required, as shade
cloth is not considered a solid roof structure.
Limitations:
- Can be affected by hail damage and machinery exhausts.
- Shorter lifespan compared to a solid-roofed structure.
- If not well-designed and constructed, shade cloth can rip in high
wind.
Solid roofed structures
Strengths:
- Offers significant protection from both solar radiation and wet conditions.
- Improves the operating environment for milking staff.
- Much longer useful lifespan than a shade cloth structure.
Limitations:
- A building permit is required.
- There is a significant cost to build and it may take several weeks to build.
Keys to success
Shade cloth structures
- SEEK PROFESSIONAL
advice
from a registered engineer and/or builder.
- USE SHADE cloth
with a
minimum solar rating of 80%, minimum 300 GSM (gram per square metre),
and at least a 10-year warranty against UV degradation. Green or black
material is preferred.
- APPLY SUFFICIENT
tension
to shade cloth to prevent damage during windy conditions. Monitor
tension regularly, especially after strong winds.
- MINIMUM HEIGHT
should be
3.6 m (ideally 4 m) to allow for adequate airflow under the structure,
effective use of sprinklers and fans, and good machinery access.
- A PITCHED roof is
better
than a flat roof as it enhances convective air movement.
- SUPPORT POSTS used
should
be structural grade steel. They should be located outside the dairy
yard to prevent contact with manure and water, and so they don’t
interfere with yard washing.
- DEEP FOOTINGS
should be
left to cure for an extended period (at least 2-3 weeks) before bearing
any load.
Solid-roofed structures
- USE ALUMINIUM or
white
galvanised iron sheets to increase the rate of solar reflection.
- MINIMUM HEIGHT
should be
at least 3.7 m at lowest roof height and at least 4.5 m along the
centre to allow for adequate airflow underneath the structure,
effective use of sprinklers and fans, and good machinery access.
- ROOF PITCH should
be at
least 20° (ideally 30°) to enhance air movement.
- A CONTINUOUS ridge
opening will promote convective heat dissipation via the ‘stack effect’.
- GUTTERING AND
downpipes
should comply with the state plumbing code.
Damage to shade cloth caused by
tractor exhaust.
This shade cloth
structure is only 3.5 m high.
Damage to shade cloth caused by
poor maintenance.
Ensure that springs
that become detached are re-attached
as soon as possible.
|
