Nutritional characteristics of selected species of Acacia growing in naturally saline areas of Western Australia

Abstract

The forage potential of 11 species of Acacia from naturally saline areas of Western Australia was assessed by analysing their nutritive characteristics and acceptability to sheep. The crude protein content of new shoots was greater than that of mature phyllodes [8-25 v. 6-12% dry matter (DM) respectively]. This was reflected in higher in vitro DM digestibility (IVDMD) values (34-59% in shoots v. 22-54% in phyllodes). IVDMD appeared to be reduced by high concentrations of neutral and acid detergent fibre (NDF and ADF) and acid detergent lignin (ADL). The least acceptable species generally had high values of NDF. The most promising species for use as perennial fodder shrubs were Acacia ampliceps, A. brunzalis, A. cyclops and A. ligustrina. Mature phyllodes of these species had IVDMD >40%, ADL <20% and crude protein level of all foliage in the range 8-17% DM. A. patagiata and A. ixiophylla were acceptable to sheep; however, crude protein levels and IVDMD of phyllodes were relatively low. Although new shoot material of A. eremaea, A. inceae, A. aff. lineolata, A. mutabilis and A. redolens had relatively high levels of crude protein, mature phyllodes of these species had low levels of protein, IVDMD <40% and high NDF concentrations (>50% DM), which suggests that these species would be unsuitable as animal feed. The ability of salt-tolerant acacias to grow in marginal land means they may provide supplementary forage in times of drought.