The business of producing sugar takes and makes a lot of energy and produces a huge amount of waste and by-products.
“We’re budgeting to crush this year 1.5 million tonne of cane over a 25-week period,” Mark Gayton, Factory Manager of Racecourse Mill in Mackay said.Could sugarcane waste provide a value-add for growers and alternative to hay or feed?
“Typically, on a daily basis we’re processing about 11,000 tonne a day and out of that we’re probably getting 40 per cent fibre so typically we’re producing 1,800 tonne a day of bagasse.”
But scientists are looking at ways of turning sugar cane bagasse and trash into valuable animal feed.
“Elsewhere around the world, we know that cattle production often goes hand in hand with sugar mills,” QUT Senior Research Fellow Dr Mark Harrison said.
“We know that sugar mills are already providing molasses into the cattle feed industry, and bagasse is another opportunity to have the sugar cane industry supply ingredients for cattle feed.”
To turn bagasse into something nutritionally beneficial for livestock — like cattle, pigs and poultry — it needs to be made more digestible.
Scientists at the Mackay Renewable Biocommodities Pilot Plant are using elevated heat to break apart the bagasse, so the sugars it contains are more accessible for the animal that’s eventually going to eat it.
“We can put it under high pressure and high temperature for a short period of time, then we release that pressure and the particles, the fibre, explodes and breaks open and so that physical change in the fibre is what improves its usefulness as a feedstock for a whole bunch of processes, including 2G ethanol.”
But it’s the potential to enhance the nutritional worth of low-value crop residues that presents opportunities for canegrowers, sugar manufactures and livestock producers.
“Our global population is expanding and Australia is really, really well placed to supply animal products to the world. But to do that we need more feed,” Dr Harrison said.
“A lot of the current ingredients we have in feed are some of the ingredients that we put in human food, so if we want to increase our animal production capacity here in Australia, we need to think very carefully about what we’re feeding those animals.”
“We need to look to residues and by-products from agricultural systems that are available at central locations like sugar mills, as potential feed additives, potential feed ingredients.”
Improving the nutritional quality of bagasse
At the Queensland University of Technology’s Brisbane labs, Associate Professor Dr Robert Speight leads a team working to further improve the nutrition qualities of bagasse.
The scientists have looked at raw bagasse, and what organisms already grow in it naturally, and used that information to develop probiotics to help make the bagasse more nutritious.
“What we want to do is add the probiotics or the enzyme supplements into that so that they start to grow at a faster rate, so that means they’re more productive animals for the farmer and more profitable,” Dr Speight said.
“Waste is a massive issue at the moment in society, it’s very much on peoples’ minds. For industry it very much comes down to the economics.
“Everyone wants to make as much profit and as much money as a business as you can so any opportunity to take something coming out as a waste — either as a cost, or low value co-product — if we can turn that into something of high value with an economic process — that’s more money for the business.”
Canegrowers are hopeful the research will lead to real-world opportunities for value adding.
“It’s extremely important, research is the future,” Joe Muscat, a canegrower from Oakenden in central Queensland, said.
“Without good research we’re really going to be left behind.
“You know bagasse is the waste stream of that processing, if we can add value to that waste stream, it certainly has a huge impact on the profitability of the business so I think it’s terribly important.”
Large-scale trials of the bagasse-based animal feed are the next big goal.