Sandra, allthough I do feed some fruit and vegetables and grain, I don't do so for the vitamins! 100g of ox liver and 100g of ox heart contain many more vitamins than do 200g of any vegetable I can think of. The only vitamin a dog would not get that way is vitamin C, and a healthy dog doesn't need that, because he can make it himself.
There are various reasons for feeding some plant material, but supplying the dog with vitamins is not one of them as long as you feed liver and heart. But I have noticed that many barfers seem to believe in this myth.