BRAND...and SIZE of bag. You can pay $2/lb. for IAM or other top brands in a small bag. Or you (I) can pay 33c/lb. for "Old Yeller" (KRoger) or "VALU" dogfood in large bag, with same protein/fat/fiber %s as Brandnames. (I feed a half-dozen large dogs). The pertinent question is WHY is CMG so expensive..selling essentially "cheap" latino food, evolved for a population that had to subsist on beans, cornmeal, and doctored-up cheap meat.