
What sort of food is it? I am feeding mine Burns dry food (Lamb & Maize and Fish & Maize at the moment) and just checked the fish one it contains 70% Maize, 18 % Fish meal, Peas, Fish Oil, Sunflower Oil,Seaweed, Vitamins & Minerals.
If it is wet food then it could be water and these cerial fillers, if it is dry food, then it seems a big difference...
Have the producers got a website? Try and check it on there, sometimes they explain their food a bit more than on the packaging itself.