Native Australian shrub legume species may provide an alternative feed source for livestock

Abstract

The feed quality of a variety of native shrub and herbaceous legume species from the Riverina area of southern New South Wales was determined to provide an indication of their potential use in livestock grazing systems. Fifteen species were sampled from each of two locations (chiefly low fertility roadsides or travelling stock reserves) at four times within a 12-month period viz. August, November, February and May according to the most likely plant parts to be consumed by grazing animals for each species. Digestibility was estimated using an in vitro rumen fluid digestion assay and crude protein was estimated from nitrogen analysed using the Dumas combustion method. Digestible organic matter in the dry matter (DOMD) was greater than 550 g/kg dry matter (DM) for seven of the native legume species and was highest for Daviesia spp. (D. latifolia 696.2 ± 15.0, D. leptophylla × latifolia 642.5 ± 15.1 and D. leptophylla 622.7 ± 15.4), Glycine spp. (G. clandestina 628.2 ± 18.1, G. tabacina 621.9 ± 28.0 and G. canescens 580.4 ± 25.4) and Indigofera australis (617.8 ± 15.3). Crude protein content was greater than 80 g/kg DM for all species analysed, suggesting that these plants are able to fix nitrogen under low phosphorus fertility conditions. Studies examining grazing management as well as nitrogen fixation and nitrogen transfer to companion grasses are required in order to optimise the management of these plants in grazing systems.