A protein supplement such as lupins is needed, especially after the better quality feed has been eaten in the first two to three weeks. Where a limited amount of supplement is being fed it is important to make sure all lambs receive an equal share. Trail feeding twice a week may be the best method. Lupin stubbles provide an ideal source of feed for lambs provided there is no risk of lupinosis. Lupinosis damages the liver and may cause yellowing of the carcass which is not acceptable to the lamb market and reduces growth rates and feed conversion efficiencies.
Lambs take three months to recover from even mild cases of lupinosis.
Nevertheless, with lupinosis-resistant varieties of white lupins and a good understanding of the predisposing conditions for lupinosis, lupin stubble can provide a very opportune finishing system for out of season lambs. No additional grain source is needed as protein and energy levels are suitable for good growth rates. It is important to monitor the level of lupin seed on the ground and move lambs on before it gets down to four lupin seeds per tenth of a square metre. When lambs are allowed to select their own diet, such as on a stubble paddock, they will consume 30 - 40 per cent roughage. This is a higher level than fed in feedlots and because the roughage component is normally the lowest energy component of the diet this limits growth rates.