In mixing poultry ration-as is indeed the case of all livestock feeds-one must make sure that final mixture is palatable and easily digestible otherwise the meal will be rejected and therefore be useless to the chickens.
Also note that chickens do not like too finely ground meals. Mashes containing considerable bulk are preferred by the chickens, such mashes may contain up to 40% bran which provides bulk as well as keeping chickens in a clean active condition.