# Use of a Simple Model of Continuous and Rotational Grazing to Compare Herbage Consumption

1993

## Description

A simple mathematical model (a linear dynamical system) was constructed to predict herbage consumption by grazing animals. This model was used to compare 3 grazing methods over a range of stocking rates at low pasture mass. The grazing methods compared were: continuous grazing (CTS), rotational grazing with equal time intervals (BQ), and rotational grazing where the time of shift was optimal for maximising intake (OPT). The rotational methods were the simplest possible, the land being subdivided into 2 fields, each of which was grazed once. The order of grazing the fields was also considered. The model predicts (I) that at low stocking rates the CTS treatment allows greater intake per head than the rotational treatments if the fields initially have unequal herbage masses, and similar intake in the other cases; (2) that at moderate stocking rates intake is similar under all treatments; and (3) that at high stocking rates· intake from OPT is greatest, followed by EQ, with CTS giving the lowest intake, although treading and fouling effects were not considered. The model also predicts that greater intake is achieved if the field with lower pasture mass (kg dry matter) is grazed first.

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Use of a Simple Model of Continuous and Rotational Grazing to Compare Herbage Consumption

A simple mathematical model (a linear dynamical system) was constructed to predict herbage consumption by grazing animals. This model was used to compare 3 grazing methods over a range of stocking rates at low pasture mass. The grazing methods compared were: continuous grazing (CTS), rotational grazing with equal time intervals (BQ), and rotational grazing where the time of shift was optimal for maximising intake (OPT). The rotational methods were the simplest possible, the land being subdivided into 2 fields, each of which was grazed once. The order of grazing the fields was also considered. The model predicts (I) that at low stocking rates the CTS treatment allows greater intake per head than the rotational treatments if the fields initially have unequal herbage masses, and similar intake in the other cases; (2) that at moderate stocking rates intake is similar under all treatments; and (3) that at high stocking rates· intake from OPT is greatest, followed by EQ, with CTS giving the lowest intake, although treading and fouling effects were not considered. The model also predicts that greater intake is achieved if the field with lower pasture mass (kg dry matter) is grazed first.