Agreed - they need to eat a lot of hay to stay healthy. I fill the hay racks for my pigs multiple times a day.
They only need one tablespoon of pellets a day so make sure enough don’t overfeed them.
They also need one cup of a variety of fresh veg a day - such as bell peppers (which contain essential vitamin c), a small amount of leafy greens, cucumber, herbs etc.
Fruits and carrots ie sugary items should not be given to them very often.