Feeding a quality feed and a good worming program should cut down on the amount you have to feed. The are alot of misconceptions with the protein % and the Fat %. Dogs cannot digest certain ingredients well which may be high in protein or fat, this includes corn. Look on the ingredients label on the dog food bag and usually the ingredient that is listed first is what the food is made mostly of.
Take a look at this, it should help clarify things a bit
http://www.peteducation.com/article.cfm?c=2+1770&aid=668
