From ErfWiki

Proposed Canon

Rations are the primary food source for Units. Rations automatically pop near the Unit they are intended to feed. Units can also cook animals to provide additional nourishment.^Erf-b1-p104 Food does not pop for captured Units.^Erf-b1-p038

Speculation

Rations normally pop at dawn.^Erf-b1-p037

Rations may also pop at the beginning of Turn.^Erf-b1-p106

With the new term Battlespace^Erf-b1-p144, and knowledge that Turn starts at dawn when enemies are not near, the rule is probably that Rations pop at the beginning of Turn, not dawn as Bogroll suggested. On Parson's first full day in Erfworld, it is likely that no enemies were within striking distance of Gobwin Knob's Battlespace yet and Bogroll knew this, so on that day the Rations popped at dawn, as they did after the battle.^Erf-b1-p144 Furthermore, at that time, the Natural Turn Order placed Gobwin Knob first, since Charlescomm was not participating and Transylvito and Jillian were both allied with Jetstone, placing their Turn with the last to take Turn which was Jetstone, so Gobwin Knob's Turn began first anyway.

Captured Units may not have Rations, because no one may be paying their upkeep. To feed a captured Unit, the capturing Side may be required to pay upkeep.