The relationship between sward structure, ingestive behavior and dietary quality in cattle grazing a Chloris gayana pasture.

Abstract

The relationship between sward structure, ingestive behaviour (bite size, biting rate and intake rate) and dietary crude protein (CP) content was studied on a Chloris gayana pasture at different growth stages using oesophageally-fistulated steers. As the pasture matured, leaf table height, plan height, disc height, stemminess and standing herbage increased while leaf density and leaf percentage (%) declined. In conjunction with these changes, biting rate and dietary CP declined sharply, while bite size increased. Intake rate remained relatively constant for all sward structures. Animals adjusted biting rates to compensate for changes in bite size and thus maintained rates of intake. Bite size and dietary CP were negatively correlated. It was argued that, in the present study, leaf table height, stemminess, leaf density and leaf % were the main determinants of dietary CP and ingestive behaviour.

Keywords: bite size; biting rate; cattle; cattle grazing; chloris gayana; crude protein; dietary crude protein; dundee research station; grazing; growth stage; herbage; intake rate; leaf table height; natal sour sandveld; oesophageal fistula; pasture; south africa; sward structure