Why does a pig wallow in mud?
It is a fact that a pig likes to roll in mud, and it enjoys doing so.
Live Science says that a pig rolls in mud to keep cool because it does not have sweat glands. Humans have sweat glands, and we sweat in hot conditions to keep us cool. But there are other reasons why a pig likes to wallow in mud.
Rolling in mud also protects the pig from sunburn. The mud provides a coating on the body to prevent the sun’s ray from burning its skin – because, although it has bristly hair, the hair is often thin and sparse.
A 2011 study conducted at the Wageningen University and Research Centre and published in the Applied Animal Behaviour Science journal showed that rollowing in mud – wallowing in mud – may also be a sign that the pig is healthy and happy.
The researchers studied 66 research papers on the wallowing behaviour of pigs, wild boar, and other wallowing species of animals. Many of the research papers wrote about the purpose of wallowing – which included temperature regulation (keeping cool), sun protection, and parasite removal.
The strongest reason for wallowing seems to be temperature regulation because pigs have few or no sweat glands, high body fat, and a barrel-shaped body that stores heat. The study found that the action of wallowing can lower a pig’s temperature by 2oC (3.6oF), which meant that rolling in a mud bath is more cooling – for a pig – than rolling in cold water. The water in mud evaporates from the mud-coated pig more slowly than the water on a pig with no mud. This means that the mud keeps the pig cooler for a longer time than just water.
Why do pigs wallow in mud in cold or cool weather? They don’t have to keep cool so, why do it? The study showed that pigs wallow in mud for parasite removal – to scrape off parasites, such as ticks and lice, off their bodies. They might also be rubbing their scent glands around the pig sty as a method of marking their territory.
The researchers added that ‘the simple enjoyment of natural behaviours might be a factor in the good life, the wellbeing, of farm animals, especially pigs wallowing in mud.
Location of photographs: Paris Zoo, France
Photographer: Martina Nicolls
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