Leucaena - Northern Australia's cattle grazing superfood

It's been lauded as a wonder plant for tropical and subtropical beef production and there is good reason why leucaena has earned this tag. It has the ability to double beef production from the same area of land by increasing stocking rates and liveweight gain.

Yet the use of leucaena is not as widespread as it could be according to Stuart Buck, whose passion is for the plant and what it can do. He's keen for more livestock producers to take another look at the plant and see the benefits of a high-protein, perennial, tough plant as a means of increasing business resilience, especially during drier times.

When implemented correctly, it has the ability to double beef production from the same area of land by increasing stocking rates and liveweight gain.

It was a soft start for the forage legume in Australia, which was first released as a perennial cattle forage in the early 1960s. Those who brought it in could see its potential but it took another three decades - into the 1990s - before it was taken seriously as a fodder choice. For Stuart, the benefits far outweigh any kind of limitations around the perennial plant, yet he feels some things have stood in the way of broader adoption.

Leucaena is the most productive and sustainable legume-grass pasture for northern Australia.

One of the barriers to graziers is the cost of establishment, which can be double that of other forage crops. Yet Stuart said this was nonsensical when it came to cost-benefit analysis. The initial investment is bigger, Stuart says, but the longevity of the plantation's life - which could be as much as 50 years or more - means that cost can be amortised over five decades.

Establishment can be difficult too, yet research and experience have been great teachers. Leucaena needs a friable and weed-free seedbed with stored soil moisture at planting to provide reliable initial growth. And to achieve germination rates of 90%, the seed needs to be treated by what Stuart terms 'mechanical scarifying'.

'This is a hard seed and scarification cracks open the hard coat of the seed and allows water in,' Stuart says.

'It's nature's way (the hard seed coat) of ensuring the longevity of the species, but by scarifying, we can lift that germination rate from 5-10% to around 90%.'

There was also a setback when early Australian trials of grazing leucaena showed cattle were not putting on weight as expected, thanks to a toxin in the plant called mimosine, which amongst other things, reduces appetite.

Researchers and leucaena fans were not put off by this; they found that goats in Hawaii were eating the plant with no problems. These goats had a special type of rumen (stomach) bacteria microflora which can break down the leucaena toxins into harmless by-products. This rumen bacteria is now available to producers in the form of a stock drench, colloquially called 'the leucaena bug', allowing them to negate the toxin and maximise weight gain.

It was the vast list of positives that outweighed the negatives that convinced people like Stuart to persevere.

So why were those driving the planting of leucaena so keen to keep jumping every hurdle? It was the vast list of positives that outweighed the negatives that convinced people like Stuart to persevere. And topping that list was the ability to increase stocking rates and liveweight gain to double beef production from a perennial plant.

The figures tell the real story.

Stuart says a grass-only grazing system in locations suitable for leucaena can produce cattle weight gains of 0.45-0.5 kilograms a day, so across 365 days, that's 180 kilograms of weight gain per animal per year.

Add leucaena into the grazing mix as well as grass, and cattle are putting on 0.65-0.7 kilograms a day, so across 365 days, it means 240-250 kilograms a year.

The bottom line was an extra 60-70 kilograms per head per year for cattle grazed on leucaena.

The bottom line was an extra 60-70 kilograms per head per year for cattle grazed on leucaena. And when this is combined with additional stocking rate, then the kilograms of beef produced per hectare are significantly higher.

So how does leucaena do this? The high protein level (20-25%) of the feed is key. Add a high digestibility of around 60-65% and cattle do well.

But one of the key benefits is when tropical grass pastures dry off and lose nutritional value in the dry season. It is here that leucaena comes into its own, extending the premium quality grazing period from four to five months for grass-only pastures to seven to eight months for paddocks where leucaena is planted too.

Leucaena produces about 4000 kilograms of dry matter per hectare, although only up to 2000 kilograms of this is edible and the remainder woody growth.

Established leucaena pasture in Banana, Central Queensland.

And just when you think it couldn't get any better, leucaena also has methane-reducing properties. Work by CSIRO researchers, in a team lead by Dr Ed Charmley at Townsville over the past decade, have shown that grazing leucaena can decrease methane reductions, helping to address a key challenge for northern Australia beef production.

It's partially to do with the increased productivity and kilograms of beef produced more quickly that helps decrease methane, but it's more than that.

Dr Charmley's work drew on the knowledge that the leucaena plant has something called bioactive compounds, which could reduce methane production in the rumen. His research tested a number of varieties of leucaena, and each of these was fed at varying percentages of the cattle diet.

The good news showed that increasing leucaena in the diet increased the amount of feed cattle ate but reduced methane at the same time.

The good news is that increasing leucaena in the diet increased the amount of feed cattle ate (better weight gains) but reduced methane at the same time. Dr Charmley's work put this down to the tannins in the leucaena which worked their magic to lessen methane production.

That's certainly a winner when it comes to the beef industry trying to meet its targets of becoming carbon neutral by 2030.

There is also good emerging data on leucaena's ability to increase soil carbon sequestration too, which is another bonus to achieving carbon neutrality.

It does require management and is not set and forget. Stuart says grazing the forage legume so that it does not get too tall is essential. Graziers using leucaena are encouraged to follow the Leucaena Code of Practice, a framework for management that was set up by The Leucaena Network about 20 years ago and is available at www.leucaena.net where more information on the forage legume is given.

It's important to not allow the legume to set seed as 'you don't want a forest of it', Stuart says.

Graziers using leucaena are encouraged to follow the Leucaena Code of Practice, a framework for management.

But like most things, the more effort you put into leucaena, the greater the rewards. The ability to provide higher quality feed for longer periods in subtropical and tropical cattle grazing operations should surely see it considered by more producers as an option for at least part of their country.

Whether it's feed quality or increased production or helping decrease methane, leucaena keeps ticking the boxes as a real player in the tropical and subtropical feed options for beef cattle.