Most of the sites that came up when I googled "study wolf diet" were in regard to how they are feeding off of cattle.
Many of them were studies on percentages of cattle vs. moose, elk, deer, and other large herbivores.
Not a single one included how much grains, fruits, and veggies a wolf consumed.
I did find one interesting site:
Wolf CountryOn their
food diet page, they do mention that wolves will
occasionally eat fruits and berries (no mention of veggies), as a
minor part of their diet. Grass is eaten to purge the digestive system.
I also found the
wolf hunting page very interesting. Consider, if wolves prey primarily on the weak/ill, what does that say for their digestive systems?
Dogs are not that far removed from wolves. I do not believe that a dog's digestive system has been so much altered that they need as much fruits and veggies as many folks claim.
.