Comparative Analysis of the Underlying Hypotheses on the Formulae for Estimating Herbage Consumption from the Change in Herbage Mass in Pasture

Abstract

The rate functions for herbage growth and consumption are determined on the existing formulae for estimating herbage consumption from the change in herbage mass in pasture. New formulae for estimating herbage consumption are also derived assuming various and possible rate functions for herbage growth and consumption. The goodness of fit of the estimates obtained using the existing and new formulae to the observed values of herbage consumption in previous papers is examined. The rate functions necessary for the existing formulae are constant and are the first-degree functions of herbage mass. When the first-degree function which is proposed as a model of herbage growth rate (Turchin・Batzli 2001) is assumed, the maximum herbage mass in pasture must be measured. When the logistic equation (Verhulst 1838) is assumed as a model of herbage growth rate, the formula for estimating herbage consumption is impossible to derive. The estimate obtained using the formula proposed by Bosch (1956) is best fitting to the observed values of herbage consumption. The formulae based on the simple and discontinuous functions are advantageous for practical use for the estimation of herbage consumption in pasture.