The feeling of hunger (or the absence of hunger) changed how much the rats valued the pellets, but it did not diminish their willingness to work. Hunger is an H&N phenomenon, an immediate experience, not an anticipatory, dopamine-driven one. Manipulate hunger, or some other sensory experience, and you affect the value of the reward earned through work. But it’s dopamine that makes the work possible at all: no dopamine, no effort.
