05 November 2018

Thermal images recorded on a number of Rattlerow’s commercial units and contract production sites during this year’s heat wave has raised pertinent questions about finishing accommodation. Jane Jordan learns more about insulation and how it might be affecting welfare and performance.


Thermal evidence. The design specifications of a building can affect its thermo-dynamics.

Heat detecting footage, taken by Adrian Lawson, Rattlerow’s joint MD, during 2018’s extremely hot summer, revealed some interesting facts about pig housing and how certain specifications can affect the thermo-dynamics of a building and ultimately the pigs’ living environment.

The thermal images, taken at varoius times of the day in semi-intensive, naturally-ventilated systems, demonstrated some very marked differences between well insulated and poorly insulated buildings.

“We recorded these thermal images to find out what was happening inside the various types of accommodation we use during these very hot conditions. The results showed us that insulation is undervalued and our mindset needs to change. We need to move away from heat retention and focus on temperature management,” says Adrian.

Revealed. How the roof line, pen divsions and the pigs stay hot even when windows are fully opened and ventilation is at maximum.

He says UK producers must understand how insulation can improve the pigs’ environment all year round as it’s as important in hot conditions as it is in cold.

“I’m confident that any investment made to improve the insulating properties of a building, whether it’s slatted, straw-based or an outdoor hut, will pay off as it will benefit production efficiency,” he adds.

The heat detecting photographs pictured here were taken during August 2018 when UK temperatures hit record highs. The footage, recorded at various times throughout the day, demonstrates how the materials used to fabricate pens, divisions and gates, and the level of insulation provided in walls, ceiling and floors, can affect air movement and heat retention/dispersion. They also highlight how some of the internal structures ‘we’ choose for ease of management, can affect the way heat is retained or dispersed inside a building.

“I’m confident that any investment made to improve the insulating properties of a building, whether its slatted, straw-based or an outdoor hut, will pay off…” Adrian Lawson

Adrian Lawson.

The evidence was startling and showed how roof insulation – if there was any – was mostly inadequate and offered little protection from the sun’s intense, relentless heat. It also revealed how certain internal surfaces reflected radiant heat, that generated naturally by the pigs themselves and added to the problem.

The smooth, light-reflective, easy- clean finishes often used to line walls and pen divides, are very good at reflecting heat back into the building. In cold conditions this ‘heat recycling effect’ is useful, but when temperatures hit highs it’s not ideal.

Other interesting observations showed how temperature levels varied considerably inside straw-based, wide-span, finishing houses, even when all windows/curtain sides were fully opened and ventilation was a maximum. The thermal images showed how ‘hot spots’ developed at ‘pig level’, in zones along pen walls and divisions – places that temperature probes find difficult to monitor or just cannot reach.

Finishers reared in systems with barred gates appeared more comfortable during the hot weather than those housed in buildings with smooth panel or PVC plank-type gates.

The pictures also indicated how solid gates in the push-through dung area – those that act as pen divides and are used to close pigs in while mucking out – can impede air movement.

Finishers reared in houses with barred /steel-tube gates appeared much more comfortable during the hot weather than those housed in buildings that had smooth panel or PVC plank-type gates.


Buffers and barriers

A good level of insulation provides an effective barrier against solar generated heat and although it won’t prevent buildings getting hot, in extreme temperatures it will slow down the rate at which internal temperatures rise or fall.

Tim Miller, environmental specialist with ARM Buildings explains:

“Good insulation will buffer temperature changes and help to maintain a more stabilised environment inside a building, which is what pigs tend to prefer. But the thermal qualities of most straw-based, naturally-ventilated accommodation is generally not considered in the same way as environmentally controlled systems, so most buildings are uninsulated shells, offering very little control.”

Uninsulated shells. The thermal qualities of straw-based systems should be considered.

Even modern, ‘freedom food’ type finishing houses with automatically controlled curtain-sides have limited environmental control. Any change in ambient temperature outside is usually mirrored inside the building.

A simple farm trial carried out by ARM, monitoring average daily temperatures inside straw yards on a finishing site in Yorkshire during winter 2017/18, showed how the temperature recorded inside the buildings tracked outside levels. The investigation, in conjunction with the farm’s vet, showed that during one very cold period the pig buildings never reached more than 10 degrees C for 10 consecutive days.

“Although the pigs had bedding and appeared comfortable, you have to consider how this prolonged cold environment affected pig behaviour, performance and feed costs,” says Tim.

Adding more bedding will help to keep pigs warm, but is this cost effective and/or sustainable if straw prices escalate, and the market becomes more competitive?

Tim Miller

At the other extreme, ARM has installed positive pressure overhead ducts that push air into buildings and extractor fans in a number of straw-based systems to speed up air flow and try and counter ‘over-heating’ problems. The modifications have proved reasonably successful, with mixed results depending on the climatic conditions, but they have helped to discourage pigs from lying in the muck passage.

Further investment in an insulated roof might have offered additional improvements by curbing the ‘solar effect’, but as Tim says this summer’s extreme temperatures have proved challenging for all pig producers.

“Good insulation will buffer temperature changes and help to maintain a more stabilised environment inside a building, which is what pigs tend to prefer…” – Tim Miller

Installing positive pressure ducts and fans can improve airflow and help reduce over heating in straw-based buildings.

These observations suggest that most semi-intensive systems are not performing as well as they could be and that warrants further exploration. Insulation even at basic levels, would certainly improve temperature control and the internal environment, of naturally ventilated/straw based rearing systems – and more so when ambient temperatures are moving between extremes during Spring and Autumn.

Insulating the roofs and walls of these buildings would help manage solar-generated heat more effectively during hot, sun-baked days, while curbing excessive heat loss during extremely cold periods.

Comfort driven

“It’s always going to be difficult to stop pigs lying in the muck passage when the heat’s unbearable and relentless. We can increase ventilation and blow cooler air into a building, but ultimately, the pigs will go where they feel most comfortable. Outdoors that’s a wallow and indoors they head for the next best thing, the cool, wet dunging area.” says Tim.

Are semi-intensive systems performing as well as they could be? Insulation at basic levels would improve temperature control and the internal environment of naturally ventilated/straw based buildings.

If the UK climate is changing and extreme conditions are set to be a frequent occurrence, the pig sector must re-evaluate insulation and learn how investment in this brilliant environmental management tool can improve performance and production efficiency and enhance welfare across all of its production systems.






Author: Jane Jordan is a pig sector journalist and technical writer