RUMINANT-livestock are the biggest culprits of on-farm greenhouse gas, but novel feed additives such as grape marc (waste) may reduce their emissions.
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An Action on the Ground project funded by the Department of Agriculture, Forestry & Fisheries' Carbon Farming Futures is investigating how to reduce the 1.5 tonnes to 2t of C02 equivalent each cow and by 0.15t to 0.2t C02 equivalent each sheep produces a year – and at the same time deliver production gains.
SARDI climate applications senior researcher Melissa Rebbeck says the three-year project Livestock and Pasture Studies to Demonstrate Greenhouse Gas Abatement, which started in June last year involves testing the effect of adding marc, lucerne offal, and other potential novel additives to animals' diet.
Research at the Victorian Department of Primary Industries' Ellinbank farm shows the ability to boost milk production by 20 per cent and at the same time reduce methane emissions by 20pc through feeding grape marc to dairy cattle for more than a month.
Two of the three South Australian producer case-studies in the project are also testing the feeding of marc – stems, skin and seeds – at about 20pc of total intake.
Ms Rebbeck says that about 200,000 tonnes of marc are produced nationally from the winemaking process, giving a cheap, easily accessible supplementary feed.
"We are a major wine-producing State and it just so happens the supply of grape marc is between October and May when there is least feed in the paddock," she said.
"SA is the driest State in the driest continent and we have just been through one of the worst summers and are finding the feeding-out of grape marc is showing promise for maintenance and production feeding when combined with other feeds."
Crushed, crimped marc sells for about $40/t and fresh marc can often be obtained free.
She says it is too early to draw conclusions on its effectiveness for greenhouse-gas abatement but is researching its potential.
"We first have to overcome some variability issues with the feed quality as it is problematic to formulate rations," she said. "Furthermore, it varies in moisture content and can look like mud when it arrives or more like dry dirt.
"It has tested farmers' inventive thinking and we are yet to come up with a foolproof method on how to feed-out this product or how to combine it with other feeds."
She says that with carbon now at $23/t under the Australian trading scheme, there is only a small economic incentive for livestock producers to change practices solely to reduce emissions. That is why this research is working with growers to identify benefits to livestock gain, reduced feeding costs and improved handling. Many in the livestock industry recognise that while there is uncertainty on future price of emissions, research and development involving local cattle producers is sound preparation.
*Full report in Stock Journal, April 18 issue, 2013.
