I tried this food (puppy formula) with my 10 month old GSP for about 6 weeks.  This food did not do a good job of maintaining her during training at all.  A lot of people claim this is a rich food, and it appears to be with over 500 kcal/cup, however I wonder about the quality of the protein, as my puppy was losing muscle mass while on this food.  She was also incredibly gassy with this food.  She did however have good stools.  It was very inefficient to feed her however, and we are looking for something else.  I wouldn't suggest this food for performance type dogs.