There are several research reports regarding feeding whole wheat to broilers, and indeed this concept is being practiced in Europe, albeit in isolated cases and with variable results.
Maize continues to be a frequently-used cereal for broilers throughout the world, and recently, there has been considerable interest in feeding cracked maize instead of finely grinding it, as a measure against increasing feed costs.
Research (Clark et al., 2009) from Kansas State University has demonstrated that feeding up to 25% cracked maize does not affect broiler growth performance, while improving feed mill output, by as much as 19%. So, there is real interest in this practice.
The question most frequently asked is whether cracked maize should be part of a pelleted complete diet, or should be mixed with pellets that contain the rest of the complete diet.
Again, results have been variable, and have to do mostly with the size of maize particles. I believe this is a very interesting topic and I would be very happy to read your own experiences!