Gippsland - How Now Gippy Now - September 2010 Edition
Reducing methane emissions from dairy cows
By Peter Moate
With a number of experiments now completed, scientists at DPI Ellinbank have information on what will and won’t reduce the methane emissions from dairy cows.
A grazing dairy cow can burp up to 600 grams of methane per day. As a greenhouse gas, methane is about 25 times more powerful than carbon dioxide and methane emissions from cows constitute about 65 per cent of the total dairy farm greenhouse gas emissions.
The Australian dairy industry is facing a future in which greenhouse gas emissions from farms may be taxed or included in a carbon pollution reduction scheme.
At DPI Ellinbank, research funded by the Australian Government (Department of Agriculture, Fisheries and Forestry), Meat and Livestock Australia, Dairy Australia and the Victorian Department of Primary Industries, aims to identify practical nutritional and management strategies for reducing methane emissions from dairy cows.
Our research has shown that cows produce approximately 23 grams (gm) of methane for every kilogram of dry matter that they eat. This rate of methane production applies to a wide range of common diets regardless of whether cows are in early or late lactation, and this relationship also applies to beef cattle.
In 1980, Australian dairy cows weighed about 500 kilograms (kg) and produced about 2800 litres (L) of milk each year with a herd replacement rate of approximately 25 per cent. In 2010, Australian dairy cows now weigh about 600 kg, produce almost 6000 L of milk each year and herd replacement rates are about 30 per cent.
We calculate, therefore, that in 1980 an Australian dairy cow emitted approximately 33 gm of methane for each litre of milk produced. But, in 2010, because of better feeding practices, genetic improvements, higher per cow milk production, and efficiency improvements adopted by the Australian dairy industry, this number has fallen to approximately 24 gm of methane per litre of milk produced.
Australian dairy farmers are to be congratulated for achieving this 28 per cent reduction in methane emissions per litre of milk. However, we need to reduce methane emissions much further.
Our research has shown that dietary fat supplements are the most effective way to achieve additional reductions since methane emissions are reduced by about 3.5 per cent for every 1 per cent increase in dietary fat.
The inhibition in methane emissions is similar when either whole cottonseed meal, cold-pressed canola meal, brewers’ grains or hominy meal is fed to cows. The inhibition of emissions persists for at least 12 weeks while the supplement is fed.
Drenching cows with tannin can reduce methane emissions by up to 29 per cent. However, tannin is very bitter and we have had trouble getting cows to eat it voluntarily.
Although monensin (the active ingredient in anti-bloat capsules) has long been thought to reduce methane emissions from ruminants, recent research from DPI Ellinbank and New Zealand has shown that monensin is ineffective in reducing methane emissions from dairy cows.
French researchers have reported that when algae meal containing docosahexaenoic acid (DHA) was fermented with rumen fluid in test tubes, methane emissions were reduced by up to 80 per cent. DHA is an omega fatty acid that is also found in fish oil. In autumn 2010, we fed algae meal containing DHA to dairy cows, and found no effect on methane emissions.
Future methane abatement research at Ellinbank will focus on identifying feed supplements and fodder crops that may reduce methane emissions and identifying cows that are efficient at converting feed to milk and hence produce low emissions of methane per kg DM of feed consumed and per litre of milk produced.
What can you do to reduce methane emissions on your farm?
- Continue doing what you have been doing: profitable farming with continuous increase in productivity and efficiency.
- Feed fat supplements during summer if profitable. For example, whole cottonseed, cold- pressed canola meal, brewers’ grains, or hominy meal.
- Maintain high quality, leafy pastures. This increases voluntary feed intake and fat content of pasture.
- Maintain herd fertility.
For more information, please contact Dr. Peter Moate on (03) 5624 2257 or email peter.moate@dpi.vic.gov.au
Photo Caption: Cow wearing a monitor to detect methane gas production
