Greener milk: How to make cow's nitrogen intake efficient

May 2, 2013 by Alexander Hellemans
Greener milk: How to make cow’s nitrogen intake efficient
Credit: Markku Åkerfelt

The amount of nitrogen that is excreted by livestock is directly proportional to the amount it is fed. This is according to Chris Reynolds a researcher in nutritional physiology of ruminants at the University of Reading, UK. He is a principal investigator of one of the workgroups of the REDNEX project, about to reach completion this year. Funded by the European Union, the project investigated ways to reduce the excretion of nitrogen by dairy animals. "Our aim was to look at management approaches so that we can reduce the amount of nitrogen we are feeding the animals," says Reynolds.

The total milk production in the European Union is 140 million tonnes per year. Nitrogen, taken up by in their fodder, mainly ends up incorporated in the that make up an important part of milk. But large amounts of the ingested nitrogen—in the form of proteins— are lost in the rumen, or first stomach, and during the cow's digestion and metabolism.

, such as ammonia, and nitrous oxide, a stronger greenhouse gas than carbon dioxide, end up in the atmosphere. leach into groundwater, and into surface water, where it causes the stimulation of excessive plant growth that uses up oxygen, affecting . Denitrification— whereby oxidation processes liberate nitrogen from nitrates and nitrites—makes natural nitrogen sources less available for sustaining crops.

An important factor in the project was to ensure that the reduced amount of nitrogen intake should not cause a loss in milk production. Therefore research focussed on improving the efficiency in nitrogen uptake by cows, reports Reynolds. "We improved the understanding of the effects of lower-nitrogen diets on the metabolism of cows," he adds "and we demonstrated that we could feed such diets without substantial losses of protein."

However, the researchers were surprised as they discovered that reducing nitrogen in forages could have a negative impact on the environment. Indeed, it increases the production of methane in their flatulences—a potent . "If you use less nitrogen fertiliser, you may produce forages that are less digestible, and therefore have a higher methane yield," says Reynolds. This complication requires further research. "We have to focus on a whole systems approach," he adds.

Experts agrees that this research has to be encouraged further. "There are not many options to reduce nitrogen emission, and this is one of the projects that appears to be promising," Peter Wizke, a researcher in Economic and Agricultural Policy at the University of Bonn, Germany, tells

Ultimately, such research may contribute to influence agricultural policy. Project scientific coordinator Cledwyn Thomas, a member of the European Association for Animal Production (EAAP), based in Rome, Italy, expects that the results of REDNEX will influence policy in animal husbandry at the regional level. Michael Kreuzer, a researcher in animal nutrition at the ETH Zürich in Switzerland, agrees that there is still a need for guidelines for nitrogen management for dairy farming, but they will have to be adaptable to the different farming methods in different countries. "It would be good to have recommendations and each country would then develop their own guidelines," Kreuzer tells

Explore further: Put more nitrogen into milk, not manure

Related Stories

Put more nitrogen into milk, not manure

May 28, 2010

The more efficient dairy farmers are in managing nitrogen, the more milk their cows will produce and the less nitrogen will be wasted in manure and urine, according a study by Agricultural Research Service (ARS) scientists ...

Study reveals cost of nitrogen pollution

April 11, 2011

Nitrogen pollution costs Europe between 70 and 320 billion euros ($100bn-$460bn) per year in its impact on health and the environment, according to a major European study launched in Britain on Monday.

Excess nitrogen fertilizer increasing warming in China

October 31, 2012

Halving the amount of nitrogen fertiliser used in certain areas of China would substantially decrease greenhouse gas emissions without affecting crop productivity and the area's natural carbon sink.

New strategy aims to reduce agricultural ammonia

May 11, 2011

As concerns about air pollution from large dairies and other concentrated animal feeding operations (CAFOs) continue to mount, scientists are reporting a practice that could cut emissions of an exceptionally abundant agricultural ...

Greenhouse gases from forest soils

April 12, 2011

Reactive nitrogen compounds from agriculture, transport, and industry lead to increased emissions of the greenhouse gas nitrous oxide (N2O) from forests in Europe. Nitrous oxide emission from forest soils is at least twice ...

Recommended for you

The astonishing efficiency of life

November 17, 2017

All life on earth performs computations – and all computations require energy. From single-celled amoeba to multicellular organisms like humans, one of the most basic biological computations common across life is translation: ...

Unexpected finding solves 40-year old cytoskeleton mystery

November 17, 2017

Scientists have been searching for it for decades: the enzyme that cuts the amino acid tyrosine off an important part of the cell's skeleton. Researchers of the Netherlands Cancer Institute have now identified this mystery ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet May 02, 2013
I'm glad that this research on how to prevent livestock waste not affect the environment without extensive livestock no control is part of the problem of global warming.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.