also, even if dogs chew the grass, they still do not get any nutrients from it because they do not have the enzymes to break it down further for the body to actually use. They do not have those enzymes because they weren't designed/made/evolved (however you look at it) to eat plant matter!!! even cows have to chew it first, then regurgitate it, chew it more, and then it goes through their whole specialized digestive system!!!!
AND...my dogs still gobbles up kibble any chance she gets (when my parents dogs eat). That DOES NOT mean that her raw diet isn't complete or giving her all the nutrients she needs. It doesn't mean that the kibble has something in it that she is lacking. It means she loves kibble (heck its like frosted flakes!) and will eat it when she can.
Like I said, continue feeding tripe if you feel necessary. It sounds like you know what green tripe is, and what is in it, but before you tell us to do more research, i think you need to do a little more research on what canines really require in their diet and what their bodies are made to digest. Yes they do require many nutrients, some that are in plant matter, but those same nutrients are also in Meat, Bones (and bone marrow) and organs =)