I give it one star because my dogs loved the stuff, but after several months on it, they all began developing odd conditions - gunk in their eyes (they've never had a problem before) and the oldest dog began having hair loss and awful lesions around his eyes, eyebrows, ears and mouth. After many vet visits, biopsies and specialist consults, the cause of these problems was diagnosed as a zinc deficiency - the only change had been the change in diet to the Core food, and our vet said to stop using it immediately. Our guys are now on other food which has a long-term track record for quality, and the older guy is on prescription zinc supplements and other medications due to the problem caused by the Core food. I would be very cautious about switching to a new food which has not been on the market very long again in the future. I contacted the company and they simply advised that the food has enough zinc, but my vet feels the formulation may not allow for proper absorption of it.