keep feeding them the same unless you NOTICE a change on them. But that's just me. If you found something your happy with, i'd keep it unless you noticed they were reacting bad to whatever changes they did to the food. Then switch. As long as our coats look good and no itching and poop is good.. i'd stay with whatever i'm feeding them.
But that's just me.
Elea, Sierra, Haylie & Kayden