Jersey heifer with a hole in her horn

Today I saw a young jersey cow who's horns looked like she had rubbed a hole in them. The horn was peeling and several layers were gone. It looked like the inside was hollow. What is that about? I've read their horns are hollow but how can they be peeling away like that? She was rubbing them on a tree but I've never heard of them breaking or splitting, or peeling like that. Is this indicative of something missing in her diet? TIA

Just found a post on family cow boards that shows pictures of how cows horns change as they age. The peeling is part of the normal growth process. I love the internet.