First off If you want rats that have less of an attitude I would invest in getting either Blue rats or dumbos both of which Normally dont bite... Even with out constant holding. I too Use (hog Feed) AKA Sow Cubes. It works wonders. Bedding I use PF chips The large flakes of pine. Less dust, better breathing, happy rats ^_^ I use racks And if you want them to be mobile just throw some light duty casters on the legs. I am building another rack tomorrow and picking up 60 more breeders. The only rats I have that bite are the ugly lab rats... unless they are dumbos...