Battle rations is a blanket term for "food" that can be easily transported and saved for a long time.
They are often used by Terran military forces on the field or during relief efforts. Battle rations can be fit into a small pack on the CMC Powered Combat Suit used by the Dominion Marine Corps. One kit generally holds enough calories and nutrients for the average soldier for 3-4 days.
Several planets have been stockpiling freighter loads of rations during the interim of the Brood War. This is likely a result of the lost of colony worlds responsible for food growth being infested or purified.
Common Rations in utility packs: