Infrastructure

Dairy yard

Case Study: Dairy yard shade cloth structure

Farmers’ names: James, Rose and Glenn

Facts about the shade structure:

Designed by: Local contractor
Built by: Contractor built steel frame on-site, farm staff assisted with the placement and securing of shade cloth over the frame; took 2-3 weeks
Lifespan: Now 13 years old and not showing any signs of deterioration; expected to last at least another 10 years

Other cooling infrastructure on this farm:

Low-pressure sprinklers along feed alleys of feedpad
Sprinklers at top of yard to pre-cool concrete, plus both sides of dairy yard
Extensive tree plantings in majority of milker paddocks

Background

Over the past 30 years extensive tree planting has been undertaken on this property, but a number of these plantings have died as a result of water stress due to on-going drought. With insufficient tree shade for the grazing rotation and the reduced availability of irrigation water, the property has had to rationalise its total irrigable area. In addition, the original Jersey herd was changed to Holstein-Friesians, which are more affected by heat stress.

These factors required a re-think about how to reduce the impact of heat stress on the herd, so alternate means of providing shade were considered.

The owners organised for their nutritionist to complete a cost-benefit analysis of the capital cost and payback of the shade structure and sprinkler system based on potential milk loss due to heat stress.

A 110 x 100 m feedpad was built in 1996 and the shade structure over the dairy yard was installed in 1997.

Do your figures before you start ...

A 20 m x 20 m yard area can be covered with shade cloth for about $17,000-$20,000 (incl. support posts, footings and concrete, shade cloth manufacture and installation with a 10-year warranty).

Comparatively, a gable-style steel roof designed and installed to meet local council building standards could cost up to about $50,000, but the useful lifespan will be around 20-30 years.

The dairy is centrally located. The top of the yard where the cows move on to the milking platform is not covered by shade cloth, however there are sprinklers located on both sides of the yard fence. These are used to precool the yard before the afternoon milking.

When temperatures reach 28-30°C, cows usually walk back to the feedpad and shaded yard at around 10.30-11 am. In summer and early autumn the herd spends about seven hours a day on the feedpad and shaded area, not including the pre-milking feeding time.

The shade cloth area is equipped with oscillating garden sprinklers that are used to pre-cool the yard before the afternoon milking and this allows cows to off-load heat via conduction through their contact with the cooler concrete surface. The feedpad has low-pressure water jet sprinklers along each feed alley.

Support posts were installed in the top section of the dairy yard so that the shade structure could be extended over the whole yard, but this has not been done. At most, a cow will spend an hour in the uncovered section before milking. The farmers feel there is no justification for extending it as the cows never show signs of heat stress when entering the platform. The overhead sprinklers can be used in the uncovered section of the yard if required.

Four oscillating garden sprinklers are mounted upside down

on the southern side of the yard (right hand side of the photo).

Southern end of the dairy yard covered with shade cloth,

feedpad in the background.

James’ comment

The cows are not stressed or spending time and energy trying to get cool. They are eating and producing milk instead!

The herd is calmer during milking, which makes the job for the milkers less frustrating and less stressful overall.

Also, we think that the cooling infrastructure has helped remove the fluctuations in our in-calf rate.

The steel trusses and support posts; 90% solar rating shade cloth cost $8,000 for materials, construction and installation in 1997 (about $20,000 in today’s dollars).

The shade cloth structure has the following dimensions:

Area under shade in the holding yard – 37 m long x 12 m wide.
Uncovered section of the holding yard – 13 m long x 12 m wide.
11 trusses were used with 3.4 m spacings.
Height of apex was 4.2 m.
Pitch of shade cloth was calculated once truss and apex height was confirmed.
Circular steel support posts were used and spaced about every 3.4 m.

Water for the property is sourced from the irrigation channel as part of the property’s allocated water.

Two pumps supply pressurised water to the property (one acts a back-up or, alternatively, they can be run in series if demand is high).

Tech screws and metal plate that attach the shade

cloth to the steel frame (shade cloth is stretched over

the frame – not attached to the apex of the frame).

Roof trusses

Comments from the experts

This property exemplifies all the key principles associated with providing shade and shelter for the herd.

In addition to the shade cloth structure over the southern end of the dairy yard, the property also has sprinklers along the feed alleys of the feedpad, under the shade cloth and on the fence of the uncovered portion of the dairy yard. Tree plantings mean that the farmers can also provide paddock shade and shelter for the herd in both hot and cold conditions.

The combination of the feedpad and cooling infrastructure ensures the herd is willing and able to eat on hot days. They would average more ‘fully fed’ days than comparable herds that have no access to shade and shelter.