WITH temperatures hitting record highs across the UK this summer, one broiler farming business was glad it had a plan in place for the extreme heat.

The UK’s climate is becoming warmer – but of more relevance to poultry producers, is becoming more extreme.

See also: How to set up and operate ventilation for poultry sheds

The UK’s highest-ever temperature was recorded this year: 40.3C in Coningsby, Lincolnshire, with much of England and Wales close to this.  

For broiler farmers – particularly those whose birds were approaching slaughterweight – such temperatures can prove highly problematic.

Without proper management of shed environments, heat stress will cause at first discomfort before affecting health and welfare and, if temperatures are not brought under control, birds will die.

‘Deeply concerning’

It is an issue that the government, NGOs, the media and consumers are increasingly aware of.

Defra has described bird losses this summer as “deeply concerning”, for example, and expects the poultry sector to implement mitigations to reduce the risk of welfare issues.

One issue is that sheds and ventilation systems have been specified with how the UK’s climate was in the past – less extreme high temperatures with less variation.  

Higher temperatures

Will Oliver

Even new sheds aren’t always best equipped to deal with higher temperatures. Something arable and poultry producer Will Oliver realised a few years into his arable family farm’s diversification into poultry.

Mr Oliver, of Swepstone Fields Farm, Leicestershire, and his family run a specialist 850ha arable farming business cropping wheat, grain maize, winter beans and potatoes.

In 2019 the farm built four broiler sheds housing about 180,000 birds at a time with the aim of getting organic manure back into the arable operation. Planning was done by Ian Pick Associates, who introduced the farm to Avara Foods, which it supplies.


Indeed, that focus on organic matter improving soil health was a significant contributor to his winning Farmers Weekly’s arable farmer of the year in 2022.

But on the poultry units, for which Mr Oliver has a full-time manager day-to-day, it became apparent that some adaptation beyond the initial install would be required to tackle higher temperatures.

Sheds were initially kitted out with underfloor heating fed by a ground source heat pump system, which can be ran to cool sheds. But Mr Oliver and his farm manager felt this and the ventilation system alone wasn’t enough.


“After a year of production, we very quickly installed a misting system. We had a few hot days and felt we were lucky with the age of our birds at the time,” he explains.

As a crop of broilers ages, stocking densities increase, and the risk of heat stress issues increases along with it.

The misting system that Mr Oliver opted for was manufactured by Lubing and supplied through poultry equipment specialist JF McKenna.

“Many people see the misting systems as quite expensive, but we consider it an insurance system. We felt that if we’d had that hot weather at a different point in the crop, it could have been costly, both from a welfare and financial point of view.

“We also use it at different times, such as at the beginning of the crop, to raise humidity.”

This summer

With the system in place, it became a case of planning as best as possible for the spikes in temperature.

The farm didn’t reduce stocking densities but again were quite fortunate in that birds were around 16-17 days when the really hot weather hit.

The first step was to cool the flooring using the underfloor heating system. “It’s almost accidental technology – the system is there for heating sheds, but it can be reversed,” Mr Oliver explains.

“It means you are cooling where the birds are – you can get the heat out of the shed a bit quicker, and we feel on a hot day it works quite well.

Instead of running tunnel fans – which may have brought lots of hot air into the sheds – the decision was taken to run normal ventilation in tandem with the misting system to keep temperatures under control.

“Our manager was quite apprehensive, but once he realised how the sheds were performing – that they could cope – we were all relatively calm.

“As we approached slaughterweight it was still hot – it wasn’t 40C, but we were still getting very hot weather, and we coped ok.”

Mr Oliver adds that the farm didn’t lose any birds to the heat, although he felt growth in that crop plateaued.

“We might not have a summer like it for another ten years,” he concludes. “But then again, we might.”

Heat stress explained

Put simply, heat stress in broilers is when they have difficulty balancing body heat production and body heat loss.

Signs that birds are responding to heat stress include:

  • Trying to move away from other birds.
  • Moving against cooler surfaces, such as block walls or into moving air
  • streams.
  • Lifting wings away from their bodies to reduce insulation and expose any areas of skin that have no feathers.
  • Electing to pant slowly.
  • Resting to reduce heat generated by activity.
  • Reducing feed intake.
  • Increasing water consumption.
  • Diverting blood from internal organs to the skin, which darkens skin colour.
  • Beginning fast panting.

What is a misting system?

Misting systems can be used at multiple points in a crop of broilers, but can be useful when the temperature outside sheds exceeds the desired set temperature in the bird’s environment.

Choosing a system that fires a fine mist rather than producing water droplets to keep litter dry is essential, so consider the system’s quality when selecting a manufacturer.

Once set up, the systems can be run alongside ventilation and aid cooling through straightforward natural evaporation to bring temperatures down – manufacturers say by about 6C-7C compared to ventilation alone. That can make all the difference during periods of hot weather.

They can also be used at the beginning of a crop to raise shed humidity – particularly useful when indirect heating systems are used which produce a more dry bird environment.