Evidence for palatability variation between the sex phenotypes of bladder saltbush from small-plot grazing trials
D. Walsh A D , M. H. Andrew B , R. Sinclair C and D. Coleman CA Centralian Land Management Association, PO Box 2534, Alice Springs, NT 0871, Australia.
B URS Australia Pty Ltd, 25 North Tce, Hackney, SA 5069, Australia.
C University of Adelaide, Adelaide, SA 5005, Australia.
D Corresponding author. Email: ems@clma.com.au
The Rangeland Journal 27(2) 89-96 https://doi.org/10.1071/RJ05007
Submitted: 23 February 2005 Accepted: 24 August 2005 Published: 21 November 2005
Abstract
This paper reports the results of the first intensive grazing trials to study palatability variation between the sex phenotypes of bladder saltbush (Atriplex vesicaria Hew. ex Benth.). The results show that Merino sheep preferentially graze female shrubs over male and bisexual shrubs in South Australia, which supports earlier paddock-scale observations made in New South Wales. Male shrubs with higher densities of flower spikes were consumed less than those with lower densities. However, when male flowers were small and/or sparse, the removal of male flowers by clipping did not significantly increase the consumption of male shrubs. Female shrubs with very low or very high densities of fruit tended to be consumed significantly more than those with moderate fruit densities. Other physical aspects such as plant growth habit and foliage density did not have a consistent influence on grazing behaviour. Chemical differences between the sex phenotypes are implicated.
The presence of palatability variation between the sex phenotypes suggests that there is potential to refine the existing use of bladder saltbush as an indicator species in southern Australia.
Additional keywords: Atriplex vesicaria, rangelands, selective grazing.
Acknowledgments
We are indebted to the Nicolson families of Middleback and Roopena stations, the many people who assisted with the field work and the undergraduate students from the 1994 and 1996 ‘Ecology and Management of Rangelands’ courses (The University of Adelaide). We thank Ian Watson and Alan Payne for reviewing an earlier draft of the manuscript. This research was funded by an International Wool Secretariat Postgraduate Scholarship and The University of Adelaide, and was conducted as part of the Middleback Field Centre research program. Animal ethics committee approval S/14/94.
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