Risk of lupinosis

Last stubble season saw many cases of lupinosis in sheep on the Eyre Peninsula with a high rate of severe cases.

Severe lupinosis and associated liver damage causes stock deaths.

Less severe lupinosis may reduce appetite and body condition, with underlying liver damage likely.

Pregnancy toxaemia in late pregnant ewes can also happen with cases of mild lupinosis.

Strategies can be used to reduce the risk of lupinosis.

Lupinosis is caused by a toxin produced by a fungus (Diaporthe toxica) formerly known as Phomopsis.

Phomopsis can infect all lupin plant parts but it is more commonly on dry stems at maturity and on pods, making stubbles the greatest risk.

In severe cases seed can be affected, so stock that are feeding on infected lupin grain can also suffer from lupinosis.

Late rain or humidity favouring fungal growth on the crop or stubble increases the lupinosis risk, even in so-called resistant lupin varieties.

Be aware that infected lupin grain or stubble remains toxic and cannot be re-grazed when conditions dry out.

Having enough lupin grain on the ground with other fodder available in the paddock (hay or green weeds) means livestock are less likely to graze the potentially more dangerous lupin stem.

Where the stubble infection status is unknown, lupin stems are the highest risk.

Having enough lupin grain on the ground with other fodder also available in the paddock (hay or green weeds) means livestock are less likely to graze the potentially more dangerous lupin stem.

Stubble stem has very little nutrition value anyway. By carefully monitoring seed quantity and grazing habits, stock can be removed before they are forced to consume stem material.

Sheep on a lupin stubble need to have at least 50 kilograms per hectare of grain available on the ground (40 lupin seeds/m2), while cattle need at least 100kg/Ha of lupin seed available in a stubble.

                                                                                                                   Reducing the risk of lupinosis

  1. Grain and stubble can be tested for Phomopsis infection prior to grazing. Testing is available from stock-feed testing providers.
  2. Graze lupin stubbles as soon as possible after harvest, before any fungal growth increases. The more rain events that occur on an infected crop or stubble, the higher the fungal infection risk.
  3. Monitor the grain and other feed available in stubble paddocks to prevent stock from eating lupin stubble stems.
  4. Avoid moving hungry stock onto lupin stubbles as they are more likely to consume stems and less likely to take the time to find grain on the ground.
  5. Weaners need to learn to eat lupin grain before they are moved onto lupin stubble. Weaners are more susceptible to lupinosis possibly because they feed less selectively and are likely to consume more stem material compared to adults.
  6. Graze paddocks sown with clean seed, with a minimum four year crop rotation.
  7. Avoid grazing last year’s lupin stubble or sowing fodder crops into lupin stubble. Take special care if grazing these paddocks and check for ‘leopard spotting’.
  8. Graze sheep in mobs of 600 or less for ease of checking, and less than 10 head per hectare.
  9. Be vigilant in monitoring stock on lupin stubbles. It is vital to move the mob a short distance, check for stragglers or weak or hollow looking animals and jaundice (yellowing of the eyes and mouth). Check them daily and move the entire mob off the stubble if they show any likely signs. There is no treatment for lupinosis.

Contact Primary Industries and Regions South Australia Port Lincoln animal health officer Pat Lawler for queries on 0408 539 060.