THE INTERDEPENDENCE OF ANIMAL INTAKE, PRE-AND POST-GRAZING PASTURE MASS AND STOCKING DENSITY

Abstract

A simple version of the model validated by Bricham et of (1985) was used to illustrate the factors affecting average daily intake of animals under different grazing conditions. The model accounts for differences in pre-grazing pasture mass and grazing pressure in describing pasture disappearance through time under grazing. Analyses based on the model showed the interdependencies between intake and pre-and post-grazing pasture mass and grazing pressure. In ewes grazing to a common residual (400 kg GDM/ha) intake varied between 1.32 and 0.75 kg GDM/h/day where pre-graze mass varied between 2500 and 1000 kg GDM/ha. It was concluded that where the objective of grazing management is to control animal intake at any level, attention must be paid to pre-grazing pasture mass in setting target residuals. Appropriate residuals and grazing pressures to achieve target intakes can readily be assessed for any pre-graze mass using the model presented. Keywords: Pasture mass, animal intake, pre-graze mass, residual, grazing pressure, stocking density, model, feed budget.