Advice on dairy buildings designed for weather extremes

Vets and consultants are urging a rethink on building design to future-proof against greater heat stress risk and drought, while allowing the cow to express her natural behaviour.

Recent modelling work suggests heat stress risk from extended hot, dry spells is only likely to worsen.

Emergency level (where cow death is likely) is predicted 100% of the time in parlours, and 92% of the time in cubicle sheds, by the 2080s.

See also: Why planting more trees could protect milk yields

Cow-centred design

Milking parlours are key hot spots © Tim Scrivener

Regardless of climatic conditions, Dr Jake Thompson, vet consultant for Dairy Insight and clinical assistant professor in dairy health at the University of Nottingham, says building designs should always place the cow at their heart.

“We should be thinking about how can we optimise those conditions to allow cows to convert those inputs into milk generation, because that’s the value on a dairy farm,” he says.

This means letting the cow express her behaviour by providing plenty of water, feed and lying space.

When heat stress is an issue, building design needs to factor in changes to behaviour, including cow bunching and water seeking.

That means providing enough space to access resources easily. This is influenced by living space, which is a proxy measure for space over and above the baseline, without cubicles and lying spaces.

Jake likens it to the number of lanes on a road: if there is limited space, the cow has to wind around obstacles, like a country road.

If she’s given a three-lane motorway, it becomes easier to access resources such as water, which takes pressure out of the system.

Although there is no set target, Jake’s research has identified behaviour and production improvements when moving from 3sq m of living space to 6.5sq m.

“The simplest way to increase living space in the short term is providing outdoor loafing spaces or collecting yards,” he says.

“Providing this in the evening, when there is low traffic through the farm, is a good compromise. However, you won’t see as much improvement as you would by providing better flow in the shed.”

Consistent environment

A raised roof with one pitch oversailing the other © David-Ball/AHDB

Ultimately, the aim should be to provide a consistent environment across a shed.

This could stop cows bunching in specific areas. Jake believes there is room for “smarter” approaches to building climate regulation linked to environmental sensors.

This could mean side-curtains, or fans used at varying degrees or turned off in specific zones, rather than having one setting across the whole building.

The fact buildings are often tacked onto each other only exacerbates heat stress and is a practice dairy farmers can ill-afford to continue, according to David Ball, lead environment specialist at AHDB.

“There comes a time in the development of a business where you stop doing the add-on bit and start from scratch. I think this increased risk of heat stress will accelerate or bring forward that rethink on many farms,” he says.

If a greenfield site is not possible, he urges farmers to think about whether air flow can be improved by removing obstacles, or opening up the sides of buildings.

On new sites, buildings should be positioned side-on to the prevailing wind, with the roof designed to facilitate natural ventilation.

David says innovative ridge designs, where one pitch over-sails the other – with a large vertical gap between the two can help air flow, while preventing rain ingress.

Cooling systems

Good natural ventilation could then be paired with fans.

He believes positive pressure tube ventilation – commonly used in calf sheds – could have a growing role in milking cow buildings as heat stress risk increases.

“I think the way forward is to use more directed ventilation. Rather than a fan that has high air speed close to the fan and quickly dissipates, positive pressure ventilation systems can channel air flow uniformly across the building,” he explains.

He thinks there is a need to research the cost benefits of these systems in milking cow sheds, along with the scope to incorporate “some kind of cooling system” so that cooled air is directed onto cows.

Such innovative approaches are likely to be necessary, particularly after modelling work found that none of the mitigation strategies used was able to prevent heat stress in dairy buildings in the 2080s (see box below).

Tim McKendrick, consultant for The Dairy Group, says parlours and collecting yards should be prioritised when looking to alleviate heat stress.

These tend to be areas of greater risk because of higher stocking rates and heat generation from machinery.

He also advises using roofing materials that reflect rather than absorb solar heat, such as insulated roof panels, solar panels or solar-reflecting roof paint.

Painting out roof lights could also be a cost-effective, short-term strategy.

Water supplies

David believes dairy producers will also need to consider building their own water supplies.

“If supply is compromised due to drought, it will be incumbent on farmers to be more water resilient and manage their own water supply and reserves,” he explains.

This could include putting in reservoirs, ponds or boreholes, all of which will require discussions with the Environment Agency.