Reaction of sheep to the consumption of Leucaena glauca Benth. and to its toxic principle mimosine

Abstract

Sheep on a sole diet of Leucaena glauca Benth. shed their fleece. The amino acid mimosine has been shown to be the depilatory agent. The depilatory effect of L. glauca was influenced by level and method of feeding. Small quantities of mimosine were excreted by sheep consuming L. glauca, but the major metabolite in the urine was identified as 3,4-dihydroxypyridine (DHP). It was established from the results of intravenous, intra-abomasal, and intraruminal administration of mimosine that sheep cannot detoxicate mimosine after absorption, but extensive degradation of mimosine to DHP takes place in the rumen. The absence of toxic symptoms in a sheep conditioned to L. glauca appeared to be due to increased detoxication in the rumen rather than to the development of an adaptive tolerance after absorption. The histological changes in the skin are described, and reasons for conflicting reports on the toxicity of L. glauca are discussed. A simple method for the isolation of mimosine from the seed of L. glauca is described in the Appendix.