I didn't mix half and half for a week, the way I do it is mix 1/4 part new food with 3/4 part old food the first day. If there are no symptoms, I mixed 1/2 of old with 1/2 of new the second day, again looking for symptoms. On one food I tried, there were too many symtoms such as excessive tearing, that I never got past the 1/2 mark, but if there are no symtoms, you would give 3/4 of the new, with 1/4 of the old, on the third day. The fourth day would be all new food, or you could continue to use up the old food, if you wish. |