Those rings may signify a laminitic event or may signify the end of an ongoing lami period, which based on the little info you've given, sounds like that is likely. Depending on how quickly her feet are growing, the change/rings happened around 2-6 months ago. Ensuring she's not overfed, correctly supplemented and kept on a low-carb, high fibre diet is so important for hooves.
She's got quite overgrown feet, so I'd be inclined to keep her well trimmed more frequently. She's quite flared all round, but it appears the top growth is a lot tighter connected, showing better diet is working. Backing up/rolling those flares so the walls aren't loaded should allow the well connected growth to come down unhindered.
Hoofrehab.com & barehoofcare.com are 2 great sites to learn a lot more about hoof care & the factors that effect this. Good Hoof Photos - How to take Good Hoof Photos
is somewhere to learn about taking good pics for critique.