Itching Relief: Cows have an itch they can't reach with their tongue, so they'll rub their head against a sturdy surface to scratch it. This is especially common if they have allergies or insect bites.
Scent Marking: Cows have scent glands located on their forehead and around their eyes, which they use to mark their territory and communicate with other cows. Rubbing their heads on objects leaves behind their scent and can be a way for them to claim their space.
Grooming and Shedding: Rubbing against rough surfaces helps cows to remove dirt, loose hair, and parasites from their skin. This can be particularly helpful during the shedding season when they lose their winter coat.
Cooling Down: Cows may also rub their heads on the ground to cool down. When they rub their head against a cool surface, it helps to dissipate heat and keep them comfortable in hot weather.
Boredom and Curiosity: Cows are curious animals and exploring their environment is one way they keep themselves entertained. Rubbing their heads on objects can be a way for them to investigate and explore their surroundings.
Overall, rubbing their heads on the ground serves several practical and behavioral purposes for cows, ranging from relieving itches to marking their territory, grooming, and staying comfortable.