But then you would still have the allergy concern and having scabby rats everywhere that are itching themselves bloody instead of eating. Chicken mash may be an ok diet for chickens, but it is not a complete diet for breeding rats that need large amounts of high-quality fat and protein in their diet to produce healthy litters. Chicken mash is also incredibly dusty, so your rats may come down with upper respiratory difficulties.

I just don't see where the benefits are to feeding that stuff.

Feed stores may not carry the rodent feed on their shelves, but if they sell Mazuri brand ANYTHING, then they can order it. Rodent formula 6F works well for breeding colonies as the protein % is 16% and is it a high-quality diet.