Свиньи валяются в грязи чтобы избавиться от паразитов и охладиться

Pigs wallow in the mud not because they are sloppy, but just for the opposite reason. In this way, animals fight parasites living on their skin – when the dirt dries, it disappears along with harmful insects. In addition, "mud baths" protect the skin of pigs from mosquitoes and allow you to cool the body in the heat.

National Geographic