Clearing the air – breeding for less methane
New evidence proves agricultural production of the potent greenhouse gas, methane, can in part be genetically controlled, say scientists in the Primary Industries division of Industry & Investment NSW (I&I NSW) .
After determining this in a first generation of bulls, they are now at the stage of breeding a second generation of low and high methane emitting progeny, for measurement next year.
To bring it down to everybody’s street level, the researchers make an interesting comparison between the greenhouse gas emissions of a six-cylinder family car and their highest methane emitters.
“Getting excited over cattle burps might seem strange to some people, but not to us,” said Dr Robert Herd (pictured right), principal research scientist at the Armidale Beef Industry Centre of Excellence.
Methane in burps and in the air that cattle breathe out is a major contributor to total greenhouse emissions from agriculture.
Two years ago, the department’s scientists had evidence that different bulls produced different volumes of methane.
So began their breeding program to produce low methane emitters.
Sons and daughters of those bulls, now “teenagers”, have just been measured for their methane production.
Offspring of the “best” bull averaged 191 grams of methane emission per day, compared with 236g/day by the offspring of the “worst” bull.
“Grams of methane per day are a bit abstract to most of us,” said Dr Herd.
“Climate scientists estimate that methane has a global warming potential about 21-times that of carbon dioxide.
“On this basis, the best group of cattle were producing the equivalent of four kilograms of carbon dioxide daily, about a quarter less than the worst, at about five kilograms a day.
“By comparison, a six-cylinder family car doing 20,000 kilometres a year produces about 12 kilograms of carbon dioxide a day.”
Importantly, the project is targeting “methane yield”.
The principal research scientist leading the project at Armidale, Dr Roger Hegarty, is quick to point out “methane produced per unit of feed intake must be reduced”.
“We want cattle that eat well and grow well, but, at the same time, produce less methane,” Dr Hegarty said.
Under Dr Hegarty’s direction, the young cattle in the department’s Angus research herd were measured for methane and feed intake simultaneously at the Grafton research station.
They were measured for methane production while consuming a roughage ration similar to good quality dry grass.
To measure methane production, researchers insert a small gas cylinder, a bit larger than a D-cell battery, into the rumen or forestomach of the animal.
Over the following days, the cylinder releases tracer gas.
Researchers measure the ratio of tracer gas to methane in the air breathed out, to calculate the rate of methane produced by the animal.
It is still early days but Dr Herd says the results “give real hope that it may be possible to breed cattle that produce less methane”.
The research team has now reached another significant milestone.
In June, Dr Kath Donoghue, animal breeding researcher at the Trangie Agricultural Research Centre, designed the matings for the next generation of cattle.
She used the “best” and the “worst” new young bulls from among those measured at Grafton to join to 250 Angus cows at the Trangie centre, and to another 250 cows at the I&I NSW Glen Innes research station.
“We are breeding a new generation of low and high methane emitting cattle,” Dr Donoghue said.
“If we get the expected outcome, that of producing some truly unique low methane-emitting offspring, it will be a world-first demonstration of breeding cattle that produce less greenhouse gas without sacrificing growth performance.”
The calves will be born early next year and will be measured for methane late in 2011.
Dr Hegarty says the project is doing much more than demonstrating the potential of conventional animal breeding to reduce methane emissions.
“In our lab, and in labs of collaborators in other States, we are investigating why some cattle are able to digest grass efficiently but seemingly produce much less methane than other cattle,” he said.
“Is it the microbe bugs in their stomachs? Is it the way their stomachs function?
“Knowing may enable us to recommend feed supplements or pasture plants that change how much methane is produced.”
Methane produced in bellies represents loss of feed energy, apart from being a greenhouse gas.
“Reducing methane production means improved efficiency of feed use, and better for the environment,” Dr Herd said.
In recognition, the project is funded by Meat and Livestock Australia and the Australian Government’s Climate Change Research Program.