Actually, a wolf (or a dingo in your case) in the wild eats meat almost exclusively. Mostly whatever they can run down and catch. The bowels of their prey contain grasses and leaves, and possibly a minimal amount of grain, less than 2%.
Grains are bad because a lot of dogs are sensitive to them and it causes hot spots and raw itchy skin, among other things. I would never ever recommend that they be fed them. There is no reason to be fed them.
A good rule of thumb when shopping for dog food is that if its on a grocery store shelf, its usually chalk full of grains and meat by-products aka very very crappy. Meat by-products are usually what is left over from butchering an animal and can't be sold for human consumption. Stuff that isn't very good quality.