An analysis of cattle live-weight changes on tropical grass pasture during the dry and early wet seasons in northern australia: 1. The nature of weight changes

Abstract

SUMMARY Studies were conducted to elucidate the nature and cause of the drastic losses of live weight of cattle grazing buffel grass pastures after first rains at the end of the dry season in northern Australia. This paper examines trends in weight and body composition during the dry and early wet seasons; it shows that although most of the loss in fasted live weight occurred just after first rain, most of the loss of body solids, mainly fat, had already occurred by this time. Losses of body solids in the dry season were not fully reflected in live-weight losses because of increases in total body water and in gut ‘fill’. The greatly accelerated weight loss in the period following first rain appears to have been due mainly to a large reduction in gut contents. Empty-body weight actually increased during this period owing to increases in tissue water. Continuation of this trend in tissue water into the early wet season resulted in the rate of live-weight gain greatly exceeding that of body solids.