Animal grazing selectivity and plant chemistry issues impact on the potential of Rhagodia preissii as an anthelmintic shrub

Utilization of the halophytic shrubs Atriplex nummularia Lindl and Rhagodia preissii Moq as crops in salt-affected semi-arid regions: How temperature, salinity, seed weight and size affect seed germination

The perennial halophytic shrubs Atriplex nummularia and Rhagodia preissii are native to Australia and can be planted on saline land to produce sheep and cattle feed during the autumn. However, an impediment to the adoption of the species on saline land has been the challenges in achieving successful establishment by direct seeding due to a lack of knowledge of the optimal conditions for germination. Therefore, the optimal germination requirements in relation to temperature, salinity level and seed size was assessed for each species to ascertain the optimal conditions for successful establishment by direct seeding on saline land. Seeds of both species showed optimal germination temperature at 10°C. Atriplex nummularia seeds were more tolerant to temperatures above or below 10°C than R. preissii. The germination percentage of A. nummularia was unchanged at 0-200 mM NaCl₂. The germination percentage of Rhagodia preissii declined when the NaCl₂ content exceeded 50 mM. There was no correlation between seed size, germination and emergence for any of the species. Based on the study, we suggest that sowing operations are performed during the cold winter months in subtropical areas or autumn and spring in temperate areas, to improve the successful establishment of these shrubs by direct seeding.

Australian perennial shrub species add value to the feed base of grazing livestock in low- to medium-rainfall zones

Australian native perennial shrubs that are adapted to drought and infertile soils contribute nutrients to grazing systems that would otherwise support limited ruminant productivity. In this study, we report the nutritive value of 39 Australian shrub species of the genera Atriplex, Rhagodia, Maireana, Chenopodium, Enchylaena, Acacia, Eremophila, and Kennedia. Edible foliage was sampled in winter and summer, and there was little difference in nutritive value between seasons. The in vitro organic matter digestibility of most shrub species was 40–70%. Most species contained medium to high levels of crude protein (12–22% of dry matter, DM) and high concentrations of sulfur (2–8 g/kg DM). In an 8-week grazing experiment in which Merino wethers grazed a ‘shrub system’ containing four shrub species and a sown inter-row of annual pasture, the sheep gained weight during autumn without supplementary feeding. By comparison, sheep fed senesced volunteer pasture and supplementary cereal grain only maintained weight. The forage shrubs provided up to 50% of the total DM intake of sheep grazing the ‘shrub system’ and made a modest contribution to the digestible energy intake of the animals and a large contribution to their crude protein and mineral intake. Considering the timely and predictable provision of limiting nutrients and benefits such as gut health and the provision of shade and shelter, we suggest that Australian shrub species can make a valuable addition to the feed base of low- to medium-rainfall zones in southern Australia.