Some nutritionists suggest that pet owners periodically switch between 2 or 3 different foods. This is recommended as a safeguard against unknown imbalances of nutrients that may occur when feeding the same product long term.
When changing diets, replace a small portion of the old food with the new food on day 1. Increase the percentage of new food by 10-20% each day to facilitate the change over a 5-10 day period. This will help to prevent digestive problems.