I'm pretty sure most of you feed the same formula for months (years?) at a time once you find one that "works." Among my several perhaps erroneous preconceptions about feeding was the idea that you should rotate protein sources every so often or else the dog might eventually develop an intolerance to the formula, if not the meat source in it. Since changing brands has always brought me nothing but heartache in the past I'm content to feed some variant of Pro Plan Sport with chicken indefinitely but I'd switch to the salmon or lamb formula every few months if that would be advisable.
Whatever kibble I feed I do tend to add plain yogurt, cottage cheese, eggs, sardines, "healthy" scraps and different "flavors" of canned (in moderation) so maybe that automatically helps mitigate the potential for protein intolerance. Be that as it may, I like feeding the additions; I haven't completely given up on my tendency to tinker.
FWIW, I emailed Dr. Tim (Hunt) of Iditarod and dog food fame, about this and he replied:
"I think with some dogs that idea [of rotating formulas] may have merit. Some dogs have a higher incidence of allergies due to food, for instance. Wish I could be of more help but the science can be guesswork at times."
So maybe kibble rotation is just another foo-foo notion, eh?
