ABSTRACT
This chapter presents a brief history of the submodels contained in the GRAZE model and describes the logic and mathematics of the model as related to quantifying biological processes. The GRAZE model creates composite forage composed of weighted averages of all plant attributes that influence animal selection of forage and response to plant quality. The major divisions of the GRAZE interface logic relate to plant quality and the conceptual division of a pasture into partial grazing areas. GRAZE may be used to simulate forage growth without grazing, or beef animal growth in a feed-lot situation. The biological processes of the beef animal in the GRAZE model may be quantified using Body composition, Heat transfer and thermodynamics, Intake and digestion and Energy and nutrient priorities. The plant/animal interface simulates selective grazing and is based on the concept that an unbound grazing area may be conceptually divided into subareas or "partial fields" that are created during the grazing process.
