While the recent hot weather is welcomed by many, the effects of heat stress on pigs can be profound and can compound the effects of seasonal infertility, warns ACMC veterinary consultant, Paul Thompson. Heat stress in boars can reduce both total sperm count and ejaculate volume and reduce implantation in gilts. Reduced appetites among sows in the farrowing house will result in lowered overall feed intake and longer weaning-to-service intervals, which correlates with depressed farrowing rates He therefore suggests serving extra gilts to compensate for expected shortfalls and advises monitoring temperatures in key areas. Producers should consider feeding sows late in the evening when temperatures have dropped. Where possible, evaporative cooling and misting should be carried out to keep the temperature down.