Feeding Leucaena to manage the rumen for maximum beef profit

Abstract

Leucaena leucocephala, a perennial browse legume, represents one of the few nutritional options to significantly improve beef productivity in northern Australia. This project used expert knowledge and existing spatial data sets to map potential distribution in Queensland, the Northern Territory, and northern Western Australia, estimating that up to 27.3M hectares of land in Northern Australia could viably support Leucaena-grass pasture grazing systems. This included 4.6M hectares in humid coastal areas of Queensland that are suitable for the psyllid-resistant Redlands cultivar, with economic analysis of further adoption suggesting a total benefit of $61-123M over the next 40 years across northern Australia.

To maximise the benefits for cattle grazing Leucaena, the cattle need rumen bacteria capable of degrading the toxins mimosine, 3,4 DHP and 2,3 DHP. This project investigated the effect of the Redlands cultivar on the current DAF inoculum resulting in the development of a new mixed bacterial inoculum (TriMix), adapted for better utilisation of the three different Leucaena cultivars, Redlands, Wondergraze and Cunningham. An on-property survey of the presence of de-toxifying bacteria in the rumen found that cattle which had never been exposed to Leucaena did not possess rumen bacteria able to degrade the toxins 3,4 DHP and 2,3 DHP so would benefit from receiving the Department of Agriculture and Fisheries Leucaena inoculum if being moved to a Leucaena-grass pasture grazing system.