High temperatures trigger heat stress in pigs, affecting their physical health

The high-temperature environment from June to September each year disrupts pigs' sex hormone secretion, throwing their normal estrus mechanism out of order, so that estrus symptoms become inconspicuous or the animals do not come into heat at all; high temperatures make pigs devote most of their energy to resisting heat stress, correspondingly weakening their other bodily functions, and for lactating sows and fattening pigs that need to eat large amounts of feed, this leads to insufficient nutrition and the phenomena of low milk output and slow growth; high temperatures make heat dissipation from the boar's testicles difficult, intensify sperm metabolism and shorten sperm lifespan, so that the motility of ejaculated sperm decreases or the sperm even die; high temperatures also increase the death of newly fertilized eggs and make implantation of the fertilized eggs more difficult, thereby lowering the conception rate of summer breeding.