SOUTH American beef and dairy farmers are seeing impressive results from leucaena, incorporating the high protein fodder tree into silvopastoral systems.
The breakthrough system is being promoted as a means of significantly increasing livestock productivity, while also helping improve both plant and soil health.
Silvopastoral systems integrate trees with forage and livestock production and were a popular talking point at the recent International Leucaena Conference in Brisbane.
In examples presented by Alvaro Zapata Cadavid from the Colombian-based research and extension organisation CIPAV, leucaena was playing a vital role in helping to boost both farm incomes and transform often degraded landscape.
On the El Porvenir farm in the Caribe region in northern Columbia, steers initially weighing 180-250kg acheived daily weight gains of 524 grams/day on a 724mm (about 28 inch) average annual rainfall.
More impressive was that since the project began 12 years ago the farm went from a highly eroded, non-productive landscape lacking in ground cover to a highly sustainable, heavily pastured operation. The health of the soil also improved dramatically. Organic matter went from a lowly 0.4 per cent to 2.59pc.
The silvopastoral system on El Hatico farm, which receives 750mm of rain a year, supported 220 dairy cows producing 10L/day. Running 4.3 head to the hectare, the landscape was producing 15,000L/ha/year while maintaining a 395 day calving interval.
In the higher altitude, high rainfall Andean region, 147 cows were were grazed at 4.3/head/hectare producing 10.7 litres/milk/day on Lucerna farm. That system produced 17,000L/ha/year while the herd maintained a calving interval of just under 13 months.
On El Chaco farm a combination of leucaena, teak and neem trees in addition to panacium and star grass pastures were able to sustainably support 70 cows to produce 13L/milk/day. The herd was run at a stocking rate of 3.5 cows/ha with a calving interval of 380 days.
Asturias farm, which cops 1800mm of rain a year, is another dairy operation that has been transformed. The forage tree and grass grazing system is running four cows to the hectare, producing 13L/milk/day.
Mr Cadavid said while the benefits of leucaena were well recognised in South America, there were still many challenges in establishing silvopastoral systems in Columbia.
He said the high cost of establishment and poor management decisions, particularly relating to overgrazing, could eventually bring silvopastoral systems undone.
“Ideally we need rotational grazing for one to three or five days and a rest period of 42 to 50 days,” he said. “And we need to manage the proper stocking rate.”
Mr Alvaro said while the nitrogen fixing leucaena was often called the miracle tree, it was not.
“It is just a wonderful tree for a wonderful system,” he said.
Interestingly, Mr Cadavid said cattle in Columbia are not innoculated with a rumen bug.
In Queensland, it is still recommended that cattle to be grazed on leucaena-based pastures be drenched with a probiotic containing a bacteria that can break down a harmful amino acid, mimosine.
Mimosine, which causes hair to stop growing, was investigated by the CSIRO as a way of a chemically shearing sheep.