Selcection of diet by sheep grazing semi-arid pastures on the Riverine Plain. 3. A bladder saltbush (Atriplex vesicaria) - pigface (Disphyma australe) community

Abstract

The diet selected by sheep grazing a pasture community dominated by bladder saltbush (Atriplex vesicaria Hew, ex Benth.) and pig-face (Disphyma australe (Sol.) N.E. Br.) was determined by botanically analysing the extrusa from Merino wethers fitted with oesophageal fistulas. Quality of the pasture and of the forage consumed was assessed from the nitrogen analysis of samples of material hand-plucked in the field, and of extrusa from the fistulated sheep. Results showed that in spring almost half of the forage consumed consisted of minor species which represented only 4 per cent of the pasture. In summer, when very little other material was available, Atriplex vesicaria made up 90 per cent of the diet. Disphyma australe contributed little to the diet at any time. At no time did the level of crude protein in the diet fall below that necessary for maintenance of sheep although the sodium content of the plants available in summer was high.