Infrastructure

Paddocks & laneways

Case Study: Portable shade structures

Farmer’s name: Frank

Facts about the structures:

Designed by: WA Department of Agriculture staff
Built by: Vasse Research Centre staff and some made commercially
Lifespan: Now 9 years old; expected to last another 10 years with some maintenance

Other cooling infrastructure on this farm:

Sprinklers in dairy yard
Fans over bails in dairy

Background

With little tree cover on many parts of the farm and none in the centre pivot area, a number of paddock shade structures were built in 2001 at the cost of about $5,000/structure.

Shade structures are used between December and March and on average are used by the cows for about 3 hours/day – generally between 11 am and 3 pm.

Once built, the structures have practically no running costs and are moved around the farm by four-wheel motorbike as required.

Shade structures are located in the laneway adjacent to the centre

pivot so cows can seek shade after their morning grazing.

The dimensions of the shades used on this farm are:

Base frame: 150 mm x 50 mm
Main supports: 50 mm x 50 mm
Shade frames: 25 mm x 25 mm
Pitch of shade cloth: about 30%
Tension applied to shade cloth
Length of shade: 8.0 m
Width of shade: 4.0 m
Vertical height: 3.2 m in the apex
Total length including draw bar: 9.0 m

Shelters are high enough so that heat is not reflected from under the roof back down onto the cows, and cows do not interfere with the roof structure if riding on the back of another.

Frank’s comment

When we bring them out for the first time at the start of summer, the cows run over to the structures before they have even been set up!

They obviously enjoy the comfort they get from the shades.

What would you change?

Knowing what you know now...

Frank suggests that it is important to remember that lots of building materials deteriorate in the sun.

The rope and plastic latches used to fix shade cloth were affected by UV radiation and had to be repaired or replaced every one or two seasons. Frank recommends using pre-tensioned cables to fix shade cloth to steel frames.

Also, use second-hand wheels and tyres where possible. Standard fit Holden rims are good – they are cheap and readily available.

Frank’s management tip

Use latches or chains to prevent shade structures from being blown off their support beams / trusses. These structures may not be suitable for farms that regularly experience high winds.

Hooks and eyelets attach the shade cloth securely to the frame.

Struts ensure that flapping is kept to a minimum.

Chains used to prevent roof spans from being blown off the support trusses.

Shade structures are lifted using a cantilever system.

Comments from the experts

The portable shade structures suit the needs of this farm very well.

Shade cloth is porous, which enables heat that is evaporated from cows underneath to vent through the cloth. This reduces humidity underneath the shade cloth and creates air movement by circulating air from the sides of the shade structure up through the material. Cows can off-load heat by means of evaporation and convection.

The small amount of radiation that penetrates through the shade cloth assists in drying out the earthen surface beneath. This improves cow comfort and reduces the risk of mastitis outbreaks.