Diamond is the brand many pointing dog kennels and trainers use. Or did, at any rate, until the 2005 aflatoxin recall in which a number of dogs died as I recall. I no longer use it.
No one that is any good and knows what they are doing feeds Diamond. It is pure crap. You might as well feed sawdust... The ONLY reason anyone feeds it is because it is dirt cheap. And in this case, you get what you pay for.