I have decided to switch harley to the nutro ultra as you all know.. well he ate it the first day i brought it home. i was out of puppy chow so gave him just nutro.. he hasnt ate in 2 days. so i went out and bought the puppy chow (very small bag) and mixed half and half and he ate it fine.. but how long will this continue?? will he ever eat just the nutro :?: