I change Franklin and Maggie's food every 2-3 15lb bags. We change flavors first and when I've gone through all the flavors, we change brands. I think it's important for them to have variety, and also so that they do not develop an allergy.
Just remember when you do decide to change that it should be done very slowly. Start by adding 1/4 new food to 3/4 old food. Then after a couple of days transition to 1/2 and 1/2 and finally 3/4 to 1/4. This should be done over the span of one or two weeks. |