Nutrition and Supplementation

Farmers find saltbush-based saltland pastures of most benefit during late summer and autumn. At this time, green feed is absent, stubbles have been utilised and farmers generally have to feed out hay or grain. Saltbush-based pastures provide a welcome source of green feed and a good source of crude protein.

However there are attributes of saltbush that mean grazing is not as simple as putting the sheep in the paddock and shutting the gate. Saltbush leaves have high salt concentration (up to 30%). Because sheep can only consume up to 200 grams of salt per day, they can not eat enough saltbush to achieve weight maintenance (Masters et al. 2005). This means a high energy, low salt supplement is needed to maximise the utilisation of the saltbush. This can be achieved in two ways:

In less saline sites, growing a grass/clover understorey between wide rows of saltbush may be possible. This understorey growth can provide a low salt, high energy feed that will complement the saltbush (see photo).

On more saline sites where understorey growth is not possible, a supplement will need to be provided. Generally a good quality hay is recommended and animal house experiments have shown that combining hay and saltbush increases voluntary feed intake (Warren et al . 1990) (see photo).

Water

In addition to providing a low salt, high energy supplement, the high salt content of saltbush means that sheep will need a fresh, plentiful supply of drinking water. The fresher the source of water, the more saltbush the sheep can consume. Sheep grazing saltbush pastures can consume up to 11 litres of water per day, to assist with flushing the salts from their body.

Stocking Rates

Stocking rates of up to 7 DSE have been achieve by saltland pasture farmers, but generally the rate is around 4 DSE. This rate may be increase by rotationally grazing sheep in smaller paddocks.

On saltland pasture sites where there is a mix of saltbush shrubs and grass/clover understorey, improved animal performance may be achieved by increasing stocking rates and rotationally grazing. When saltland pastures are grazed at low stocking rates, sheep initially select the more nutritious components (grasses and clovers) before the saltbush. Research suggests that higher stocking rates and rotational grazing in these systems can reduce selective grazing. This means the sheep will graze the high protein saltbush simultaneously with the low salt understorey.

References

Masters, D. G. Rintoul, A. J. Dynes, R. A., Pearce K. L. and Norman, H. C. (2005). Feed intake and production in sheep fed diets high in sodium and potassium. Australian Journal of Agricultural Research (in press)

Warren , B.E., Bunny, C.J. and Bryant, E.R. (1990). A preliminary examination of the nutritive value of four saltbush ( Atriplex ) species. Proceedings of the Australian Society of Animal Production , 18, 424-427.