Recent heatwave conditions have highlighted problems resulting from wide temperature fluctuations in finishing houses, according to ARM Buildings’ environmental specialist, Tim Miller, who has suggested that sharp differences between day- and night-time temperatures can stress pigs, lower performance and trigger health problems.
The effects are seen more in houses where pigs are nearing their end weights, and this is exacerbated in buildings run on an all-in, all-out system that results in a high average liveweight for the house.
“The heat output from large numbers of pigs nearing 100kg is enormous,” Mr Miller said.
Badly insulated older houses are more vulnerable, especially if they’re poorly ventilated, but siting has an effect, too, especially with ACNV buildings that are sheltered from the wind.
“We’ve recorded temperatures as high as 33.5C and as low as 20C inside houses within a 12-hour period, but in autumn fluctuations can be even more severe,” Mr Miller added. “You can have 30C at 4.00pm and 16C at 9.00pm – a 14-degree drop in just five hours. There’s evidence to show that big swings in temperature have a greater impact on pig performance than high temperatures alone.”
Keeping pigs in their thermo-neutral zone between their upper and lower critical temperature is the aim and ventilation is the key, said Mr Miller. However, in the absence of air-conditioning it can’t lower the temperature below the prevailing ambient temperature.
“We’re trying to avoid a lift of more than three degrees over ambient,” he added. “Some Continental suppliers install systems with half the capacity of those in the UK, leading to temperature lifts as high as six degrees, but we try to limit the temperature lift.”
In co-operation with control specialist, Farmex, ARM Buildings is developing a fan-control program that will moderate the rate of temperature drop in piggeries during the evening, making conditions more comfortable for the pigs. Farmex has an option on its Dicam control system called rate limit’ that helps achieve this goal, and monitoring from a variety of farms has enabled this system to be further refined.