I agree with Brit, use them as training treats. However, I would not make them a staple in my pup's meals. I'm not sure what you mean by liver mix, but I would be concerned about protein/fat content, especially in addition to the RC.
Does your pup receive other treats during the day? Often picky eaters are created by constantly offering food alternatives. Pups are smart and will hold out for the "good stuff."
