AHDB has published advice warning pig farmers to take steps to protect outdoor reared pigs from the effects of hot weather.
Heat stress is caused when a pig’s body temperature rises above certain limits; in these circumstances, the pig will first increase its respiration rate in an attempt to keep cool, then search for environmental opportunities for cooling, such as wallowing, soiling their pen and lying in urine.
If the pig cannot cool itself sufficiently it will collapse and, in the worst scenario, die. Pigs subjected to high temperatures will have reduced growth rates (by up to 50g/d) and, in the breeding herd, farrowing rates could decline by as much as 25%, with litter size showing a small drop as well.
The full advice can be found here
