Defoliation is the premature removal of grass parts, usually leaves, by cutting or grazing. Cutting grass by mowing is usually a clean, uniform cut. Grazing animals are selective and do not defoliate plants uniformly or evenly. Each species of livestock interacts differently within the plant-animal-soil continuum because of the different mouth structures (tongue, teeth, lips, dental pads) and different chewing habits of animals.

The impact of defoliation can be positive or negative and proper management will direct defoliation results to be positive. Defoliation that yields positive results considers how severe the defoliation is, how often defoliation occurs, and how much time takes place between defoliation. Proper management for defoliation will produce many benefits. Just as irrigation, fertilization, and harvesting can all be done wisely or foolishly, defoliation practices must be skillful.

For maximum production, a forage plant must be able to regrow or continue to grow. Defoliation management means removing plant material so that the growth meristems needed for various plant functions are left intact. Massive leaf defoliation removes the opportunity for photosynthesis and most plant functions decline. Of course, as the plant approaches its dormancy because of climate changes, production will decline. As the growing season ends, proper defoliation practices will allow the plant to produce tillers and build up carbohydrate reserves to survive the dormancy and initiate regrowth in the next season.

Since mowing can be done too low and is very uniform, poor mowing management results in devastating damage. The basic warning for successful mowing management is to know where the growing point is and retain the growing point. Encourage a vegetative stage for as long as possible. This is easier said than done since different grasses have different growing point structures and growth requirements. So forage managers must get to know their forage plants well.