Nursing moms, weaning babies, eldery or ill ratties are often fed baby cereal for extra protien or because they aren't able/interested in eating much. I mix it in with meds to make the meds taste better.
It can be mixed with ensure, soy baby formula or water.
I usually pick the oatmeal or mixed grains for B/D months old (youngest I can find), as I don't want any/much salt.