New to pigs!

Hi guys! I'm new to owning pigs. We have recently purchased breeding stock Kunes Kunes and are loving every bit of it! They are such special animals. They have a very large pasture and have a two stall horse barn that they have stalls in. The only time there in the barn is if they need water or shade. I would like to put down some gravel behind the barn where there pool, drinking water, etc is. Its of course a high traffic area especially this time of the year. Does anyone have experience with using rock around pig paddocks? I don't want bruised feet. When horse where housed there we would never put the rock down because of that issue.