An investigation of the removal of coarse plant material from lupin stubble paddocks for the control of ovine lupinosis

Effectiveness of alpha-tocopherol and selenium supplements in preventing lupinosis-associated myopathy in sheep

OBJECTIVE

To compare the effectiveness of combined selenium and alpha-tocopherol acetate treatments in preventing lupinosis-associated myopathy in sheep.

DESIGN

Measurement of plasma muscle and liver enzymes, and histopathological examination of muscle and liver in the treatment groups.

PROCEDURE

The treatments were: subcutaneous injections of selenomethionine and vitamin E (sc(SeM+E)), an intraruminal selenium pellet and oral doses of vitamin E and intramuscular injections of selenomethionine combined with either oral doses of vitamin E (imSeM+orE) or intramuscular injections of vitamin E in an oily carrier. Another group received no supplements, while a control group was given selenium pellets on day 0 and fortnightly oral doses of vitamin E from day 0 to 72. To produce lupinosis-associated myopathy, the sheep were fed a diet low in vitamin E and given repeated injections of a crude extract of Diaphorthe toxica. Groups sc(SeM+E) and imSeM+orE were stressed by dosing with protected polyunsaturated fatty acids from day 56 onwards.

RESULTS

Lupinosis-associated myopathy was induced in all unsupplemented sheep. In these sheep the storage of Se increased and that of vitamin E decreased. The subcutaneous treatment was highly effective in preventing lupinosis-associated myopathy and also produced the highest vitamin E concentrations in plasma and liver. Supplemental vitamin E was more efficacious than supplemental Se. Concentrations of vitamin E in the livers of sheep given intramuscular vitamin E were higher than expected based on plasma concentrations. Oral doses of vitamin E proved the least effective method of increasing concentrations in liver. Lupinosis did not affect Se concentrations in liver or muscle.

CONCLUSION

The sc(SeM+E) treatment is highly effective in preventing lupinosis-associated myopathy but needs to be further assessed when selenium and vitamin E are both limiting in the diet.

Evidence that phomopsins A and B are not the only toxic metabolites produced by Phomopsis leptostromiformis

The toxicities of up to four different toxic preparations containing metabolites of Phomopsis leptostromiformis were examined in two experiments with sheep and one with rats. It was shown that the different toxic preparations containing similar amounts of phomopsin A varied substantially in toxicity. Crystalline phomopsin A was the least toxic. It is suggested that the increased toxicity of the other three preparations was due to the presence of toxic metabolites additional to phomopsins A and B. Evidence to support this suggestion is presented.

Ovine lupinosis resulting from the ingestion of lupin seed naturally infected with Phomopsis leptostromiformis

In each of 2 trials lupin seed naturally infected with P. leptostromiformis was fed to 4 sheep for extended periods as a sole ration. The levels of infection of the batches of seed used were 7% and 21% respectively. Three sheep in each trial developed lupinosis, which was complicated by nutritional imbalances and deficiencies, and other disorders.