A theoretical analysis of foraging efficiency of grazing animals

Abstract

A mathematical model of the change in quantity of forage during grazing is constructed, assuming (1) that forage requirement by grazing animals is constant, and (2) that intake is equal to requirement when forage is in free supply but (3) that below a certain supply level intake becomes restricted and is proportional to supply. Grazing efficiency is then defined in terms of utilization of the forage present at the start of the period of restricted intake. The need, or otherwise, for a high grazing efficiency can be determined, given the acceptable level of utilization of forage. A particular part of the period of restricted intake is identified; the herd has to remain until well past the end of this part period, to achieve a high grazing efficiency. Because the animals are under stress during this time, it must be made as short as possible. Some ways of doing so are discussed. Subdivision of the grazing area into smaller camps can be an effective way of increasing grazing efficiency, but this method is not the only one which is practicable and it could even decrease efficiency. A formula for calculating the required number of camps is given. It can be used to give the stocking density required.

Keywords: stocking densities|forages|veld management|methods|grazing areas|subdivisions|stresses|herds|intake rates|forage quantities|animals|grazing|foraging efficiencies|mathematical models|theoretical models|utilisations