Since 1950, leucaena (Leucaena leucocephala) has experienced a gradual rise in significance as a forage plant for feeding ruminants in tropical and subtropical locations. It was originally labelled a miracle tree due to its multiple uses, but after the arrival of the psyllid insect in the 1980s and greater appreciation of its limitations for livestock feeding due to the toxicity of mimosine, enthusiasm for this tree waned. As we began to understand how to better manage toxicity, and following the general abatement of the psyllid challenge, there has been renewed interest and utilization of this valuable plant initially in Australia and Southeast Asia, and later in Latin America.
Where it is adapted, leucaena is now widely recognized as the most sustainable, productive and profitable source of protein for ruminant production. Over the past three decades, livestock scientists and producers have greatly increased their knowledge of this plant, and the increase in new plantings has been almost exponential over time.
As a consequence, there is need and increasing requests for improved knowledge of the latest varieties, recommended management practices, and feeding systems.
The last international conference on leucaena was held in 1997 in Hanoi, Vietnam., At the time, this conference defined the current status of the genus and its potential for tropical and subtropical animal production. Since then, there has been significant new R&D and uptake of leucaena feeding by livestock producers in Australia, Asia, Latin America, and Africa.
There is so much new information that a stand-alone specialist meeting is warranted to update and inform livestock stakeholders interested in leucaena research & development and utilization. Protein deficiency continues to be the major limitation for livestock producers in tropical regions, and leucaena varieties and grazing systems have been developed specifically to address this limitation.
There are many advantages of collaborative sharing of knowledge. Countries have adopted different management and feeding strategies, and these differences are of mutual interest. Some of the major findings in Australia, Southeast Asia, and Latin America include:
- Significant long term uptake of leucaena feeding (>20 years) in all regions, including the successful feeding of leucaena to dairy cows in Latin America. This excellent practical experience and local knowledge can be shared for mutual advantage.
- New understandings of leucaena toxicity that will profoundly affect management of leucaena feeding and especially the ability to feed diets comprising 100% leucaena;
- The release of new leucaena cultivars including a psyllid-resistant variety;
- New work on low- and high-density planting configurations that influence the amount and proportion of legume and grass available for animal production. The Indonesian practice of feeding sole leucaena diets to fatten Bali bulls is of particular interest;
- In Latin America, there has been much work on the use of leucaena in silvopastoral systems. The design of such systems can be used to promote biodiversity, animal welfare, and environmental sustainability.
- In Australia and elsewhere, there has been detailed economic analyses of feeding systems involving leucaena, e.g. comparison of high value pasture fattening options in Queensland, and of silvopastoral options in Latin America.
- In Australia and Latin America, there has been extensive work on the effect of leucaena feeding in reducing methane emissions from cattle, and on the role of leucaena systems in C sequestration.
- There is significant new work on the use of leucaena as a renewable feedstock for biomass energy production.