Sandplain Lupins for Lamb Pasture

Lupins

KEY POINTS

• Sandplain lupins are a cheap, nutritious source of feed for the summer/autumn period.

• Sandplain lupins can be grazed for three to four months at a stocking rate of 10 to 15 sheep per hectare, to achieve weight gains of up to 100 grams per head per day.

• Weaners need to be monitored closely for signs of lupinosis and if it develops they need to be taken off the lupins, grazed on other pastures and not be given lupin seed.

Authors: Keith Croker, Stewart Gittins, Grant Doncon and Jeremy Allen, Department of Agriculture, South Perth

Sandplain lupins (also known as WA blue lupins) were accidentally introduced into Western Australia in the late nineteenth century. Since then they have become naturalised and grow on poor sandy soils in the West Midlands where it is difficult to get other productive pasture species to grow. These lupins are hard seeded, selfregenerating plants.

Available feed

Stands of sandplain lupins are very variable in mass and composition from site to site, and between years, but usually have high amounts of dry matter (more than five tonnes per hectare) at the start of summer. This material consists of lupin pods and stems, an understorey consisting of lupin leaf material, grasses, clover and weeds, and lupin seed. The seed has a high content of crude protein (about 32 per cent) and a high in vitro digestibility (about 80 per cent) but contains variable quantities of quinolizidine alkaloids that may give it a bitter taste.

Figure 1. Liveweight gain of Merino weaners grazed on sandplain lupins at Badgingarra from early December 1997.

Grazing potential

Grazing experiments over four consecutive summer/autumn periods (1994/95 to 1997/98) at Badgingarra demonstrated that sandplain lupins can be successfully used as a valuable feed for Merino weaners (see Figure 1).

Over the four-year period, the composition and density of the lupin stands varied considerably, but no significant rains were encountered during any of the grazing periods. In all years the weaners grazed the lupins for three to four months from early December. During three of the years, the weaners grazing at the lowest stocking rate (five per hectare) gained about 75 grams per head per day while on the lupins.

In December 1998, the performance of Border Leicester x Merino weaners grazed on sandplain lupins on a farm at Eneabba was monitored. The paddock and sheep had been subject to the farmer’s usual management practices during winter/spring. The weaners were put into the paddock at the beginning of December. The size of the flocks was adjusted to produce a stocking rate of 10 per hectare, which, based on previous results, was expected to enable reasonable growth over an extended period in summer/autumn.

The July-born weaners had been vaccinated at weaning against cheesy gland, pulpy kidney and tetanus. The vaccine contained selenium and the weaners were also given an injection of vitamin B12. They were drenched with Ivomec® when put into the lupin paddock. The weaners started the grazing period with an average liveweight of 34 kilograms, and gained about 10.5 kilograms over the subsequent 105 days. This was a growth rate of about 100 grams per head per day (see Figure 2).

Ninety per cent of the weaners were sent to the Midland Saleyards at the end of grazing of the sandplain lupins (10 per cent were considered to have not reached a saleable weight). The sheep averaged 25.5 dollars per head. This work has demonstrated that, in the absence of significant summer rain, crossbred weaners can make substantial gains in weight over three months while grazed on stands of sandplain lupins, during a period when normal paddock pastures cannot maintain significant rates of growth. This growth was obtained at a minimal cost using a feed resource that is often under-used or neglected.

Figure 2. Weight gain of crossbred weaners grazed at 10 head per hectare on sandplain lupins at Eneabba from early December 1998.

Problems to avoid

It is important that sheep grazed on sandplain lupins be checked regularly, especially late in summer and autumn, to minimise the risk of the development of lupinosis, and to avoid overgrazing with the consequent exposure of the soil to wind erosion. If lupinosis develops in weaners,growth rates are greatly reduced. Regular checks enable the early detection of lupinosis, and the sheep can be taken off the lupins before losses occur.

The amount of material on the ground needs to be monitored so that the paddocks don’t become a potential erosion risk. Moving the water point before the surrounding area is too bare will give better use of the feed while reducing the erosion potential.

Note: Sandplain lupins are very susceptible to the disease Anthracnose that has been evident in Western Australia lupin crops since 1996/97. Increasing prevalence of this disease in Western Australia is likely to reduce production from sandplain lupins. The expansion of the area of sandplain lupins and associated increased source of Anthracnose inoculum is not encouraged because this would increase the risk of disease in the white lupin industry.

Further reading

Blake, J. and Nelson, P. (1989). Sandplain lupins. Western Australian Department of Agriculture Farmnote 47/89.

Gittins, S.; Doncon, G.; Croker, K. and Allen, J. (1999). Blue lupins: a better use for an old feed. Ovine Observer,No. 8, Sep 1999.

Morcombe, P. (1989). The sandplain lupin: its nutritional value and grazing management. Journal of Agriculture, Western Australia 30, 108-110.