THE USEFULNESS OF FECAL PHOSPHORUS AND NITROGEN IN INTERPRETING DIFFERENCES IN LIVE-MASS GAIN AND THE RESPONSE TO P-SUPPLEMENTATION IN GRAZING CATTLE IN ARID REGIONS

The average daily gains of heifers and oxen on commercial and experime ntal farms in Namibia were used to indicate production differences in several areas and at different rates of phosphorus and protein supplem entation. Faecal concentrations of phosphorus and nitrogen were used t o indicate concentrations of these nutrients in grazing. Areas with hi gh concentrations of nitrogen in faeces proved to support high levels of average daily gain. Animals responded positively to phosphorus supp lementation only when faecal nitrogen concentrations were above 12 g/k g DM. Nitrogen concentrations in faeces were directly related to avera ge daily gain of heifers, but protein supplementation did not have a s ignificantly positive effect on average daily gain.