If you are already feeding another puppy food and wish to change to a Hill’s Science Plan ^™, it's best to switch gradually over a 7 day period. Each day, decrease the proportion of the food currently being fed and replace it with an equivalent amount of the Hill’s food, until at the end of a week only the Hill’s Science Plan ^™ puppy food is being fed, in the recommended amount. Always give food at specific mealtimes (3-4 a day to start with, two a day later).