Pigs wallow primarily to regulate their body temperature and protect themselves from external parasites and sunburns.  Here's why and how they do it.
Cooling Off:

• Pigs don't have sweat glands, so they use wallowing as a way to cool down.
• The moisture on their skin evaporates, helping them lower their body temperature in hot weather.

Parasites:

• Mud or water in a wallow can help to dislodge and drown external parasites like ticks and mites that may be on the pig's skin.

​Sunscreen:

• For pigs, particularly fair skinned ones, covering themselves in mud during the warmer months provides them with natural sunscreen

As for how they build a wallow:
Digging:

• Pigs use their strong, snout-like noses to dig a shallow depression in the ground, creating a small pit.

Adding Water:

• They then often use their mouths to slurp up water from nearby sources, such as puddles, streams, or troughs, and spit or splash it onto the soil in the pit.
• In captivity they are known to drag their water dish over to a rooted out hole and dump the water in to make mud.

Mixing Mud:

• By stirring the water and soil together with their snouts and hooves, they create a muddy mixture in the depression.

Pigs are incredibly intelligent animals, and wallowing is a natural behaviour that serves important purposes in their lives.

Cows! They are intelligent animals who thrive in large pastures with their herd.  Their intelligence is linked to their problem solving abilities and social behaviour.  Here are six key areas that demonstrate their intellect:

1. Social Bonds: Cows are social animals and form close-knit groups within herds. They often establish hierarchies and can recognize and remember the social status of other cows. This ability to navigate complex social dynamics demonstrates a level of social intelligence.

2. Learning and Adaptation: Cows are quick learners when it comes to finding food and water sources. They can learn to associate specific cues with rewards, such as recognizing feeding times or the sound of a feed bucket. This adaptability allows them to thrive in different environments.

3. Communication: While cows don't have a wide range of vocalizations, they do communicate through various sounds, such as mooing, to convey different messages. They may moo to signal distress, hunger, or to locate other members of the herd. Additionally, their body language, such as ear and tail positions, can communicate their emotional state.

4. Memory: Cows have good spatial memory, which aids in their ability to find their way around their environment. They remember the locations of water sources, grazing areas, and shelter. They can also recall past experiences, which can help them avoid dangerous situations.

5. Problem Solving: Cows can exhibit problem-solving skills, especially in situations that require them to access food or overcome obstacles. For example, they may learn to open gates or find alternative routes to reach a desired food source.

6. Emotional Intelligence: There is evidence to suggest that cows experience emotions such as fear, excitement, and contentment. They can form attachments to other cows and will display signs of distress when separated from companions.

All these attributes demonstrate their ability to adapt, communicate, and interact with their environment and fellow herd members in a way that is essential for their survival and well-being.