Hydration: Cows need a lot of water to stay hydrated, especially in hot weather. If they don't get enough water, they will start to drool.
Feeding: Cows may also drool when they are eating. This is because they produce saliva to help them digest their food.
Medical Conditions: In some cases, excessive drooling can be a sign of a medical condition, such as a mouth or throat infection, or a problem with the cow's teeth. If you notice that your cow is drooling excessively and it does not seem to be related to heat stress, hydration, or feeding, it's important to consult a veterinarian.