"Pigs get stressed if they become too warm," says researcher Thuy Huynh. "They go and lie on the slattedfloor, wallow in urine, eat less and grow less as well. With cooling systems, such as floor cooling, sprinkling or water baths, the pigs remain cool and grow better."
Huynh found that pigs in confinement find it difficult to lose body heat. He found that they huddled less at a temperature above 16C. At a temperature of about 19C the animalssought a slatted floor to lie on. They also wallowed in urine and became less active.
If the temperature rises further, the pigs increase their breathing rate and eat less. Finally their body temperature rises. Huynh said that a high temperature, especially incombination with a high relative humidity, results in a poor growth of the pigs.
"Providing the pig house with extra cooling in addition to the standard ventilation decreases the heat stress experienced by the pigs," he suggests in hisresearch paper. "Cooling the floor of the lying area, providing a water bath to bathe in, or regularly spraying water from a sprinkling installation cools down the overheated pigs. As a resultof this their feed intake and therefore their growth rate increases."
Pigs are highly sensitive to temperature since they cannot actively sweat and the evaporation of water from the lungs is also limited. Rapidly-growing domestic pigs also producemore body heat than their wild relatives. The fact that they are often kept close together in the pens exacerbates this problem.