Rats are omnivores although this is a matter of discussion. Some regard rats as herbivores that can easily adapt to omnivore feeding habits.
Rats learn by conditioning to associate a particular flavor with illness and other external factors. In addition, they dislike strong flavors.
The rat will engage in coprophagia. By reingesting 5-50% of its stool, the alimentary canal efficiently absorbs a large quantity of vitamins, minerals, trace elements, and other nutrients on second passage.
Laboratory rats are often fed ad libitum. Restrictive feeding, however, can contribute to an animal's longevity, in part by reducing the incidence of spontaneous tumors.