Is the feeding behavior an all-or-nothing response, or can you distinguish discrete phases of the behavior?

Feeding behavior has discrete phases of the behavior

Explanation:

Feeding behavior can be discretely phased into appetitive phase and consummatory phases.  

The appetitive feeding phase is depicts the seeking out for food behavior which helps in finding the food. The consummatory phase is further subdivided into sub-behaviors.  

These feeding phases are motivated by stimuli in the form of environmental factors (like temperature, biotic) and excitations reaching the cortex of the brain.

The all-or-nothing response is a principle which states that the strength of a stimulus does not affects the response of a nerve cell, muscle fiber.