A model of diurnal variation in liveweight of hoggets

Abstract

A simple model of diurnal variation in liveweight attributable to feeding behaviour was developed for hoggets at pasture. It depended on the assumptions that hoggets grazed during daylight, fasted overnight, lost weight according to an exponential process during fasting, and gained weight as a result of the additive effects of a constant rate of feeding and the exponential process of weight loss. In support of this, a pattern of liveweight gains from dawn to dusk and liveweight losses from dusk to succeeding dawn was noted in a group of experimental sheep. The use of the model of diurnal variation ill liveweight for standardising liveweights obtained under diverse yarding and weighing circumstances to estimated dawn liveweights is described. Also described are the expected effects on liveweight variation of absolute liveweight, feeding level, and day length, and of a particular yarding/weighing strategy.