We feed our Lab boneless skinless chicken breasts. I grill them outside once a week and store them in a plastic zipper bag. Cut them up into 1/2 inch chunks. We also feed her the thin sliced turkey breasts lunch meat.
We’ve been doing that a lot for ourselves... grill up a bunch of chicken breasts, and keep in the fridge to use throughout the week.
I boil chicken gizzards for mine for treats. Much cheaper and much, much better for them than store bought treats. Course, my rats are a tad on the spoiled side!