Abstract
The tree legume Leucaena leucocephala (leucaena) is a high quality ruminant feed, vitally important for livestock production in the tropics, despite the presence of mimosine in the leaves. This toxic non-protein amino acid has the potential to limit productivity and adversely affect the health of animals. In the 1980s, the ruminal bacterium Synergistes jonesii was discovered and subsequently distributed in Australia as an oral inoculum to overcome these toxic effects. However, in recent times, a number of factors, including: surveys of the status of toxicity worldwide; improved understanding of the chemistry and mode of action of the toxins; new techniques for molecular sequencing; and concerns about the efficacy of the in vitro inoculum; have cast doubt on some past understanding of leucaena toxicity and provide new insights into the geographical spread of S. jonesii . There is also confusion and ignorance regarding the occurrence and significance of toxicity in many countries worldwide. Ongoing research into the taxonomy and ecology of the Synergistetes phylum, improved methods of inoculation, and improved management solutions, along with aware-ness-raising extension activities, are vital for the future success of leucaena feeding systems.
Highlights
Leucaena is a multipurpose forage tree legume widely used in the tropical world (Shelton and Brewbaker 1994)
In tropical Australia, L. leucocephala ssp. glabrata cultivars were first released in the 1960s, and there are currently more than 200,000 ha of leucaena-grass pastures (Dalzell et al 2012), with more plantings each year
As a diet of 100% fresh leucaena leaves may result in consumption of as high as 0.031% body weight (BW) mimosine (Tangendjaja et al 1985), it would seem that leucaena feeding at levels greater than 50% would lead to alopecia in unprotected animals
Summary
Leucaena is a multipurpose forage tree legume widely used in the tropical world (Shelton and Brewbaker 1994). Shelton portant, as it provides edible forage long into the dry season (Shelton and Brewbaker 1994). Leucaena is a vitally important source of protein for ruminants throughout south-east Asia, China, India, Hawaii, the Pacific islands, Mexico, Central America, South America and Australia (Shelton and Brewbaker 1994). Glabrata cultivars were first released in the 1960s, and there are currently more than 200,000 ha of leucaena-grass pastures (Dalzell et al 2012), with more plantings each year In tropical Australia, L. leucocephala ssp. glabrata cultivars were first released in the 1960s, and there are currently more than 200,000 ha of leucaena-grass pastures (Dalzell et al 2012), with more plantings each year
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