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The new professor at Aarhus University wants to decriminalise cows

As of 1 September 2020, Mette Olaf Nielsen has been appointed professor in “Production and Lactation Physiology in Ruminants” at Department of Animal Science, Aarhus University. Mette will contribute to solving the agriculture’s climate challenge concerning the methane emission from ruminants.

[Translate to English:] Professor Mette Olaf Nielsen vil med sin forskning bidrage til at finde de bæredygtige løsninger i forhold til at reducere drivhusgasudledningen fra drøvtyggerne”. Privatfoto.
[Translate to English:] Professor Mette Olaf Nielsen vil med sin forskning bidrage til at finde de bæredygtige løsninger i forhold til at reducere drivhusgasudledningen fra drøvtyggerne”. Privatfoto.

As of 1 September 2020, Department of Animal Science, Aarhus University, has appointed Mette Olaf Nielsen professor in “Production and Lactation Physiology in Ruminants”. In her new professorship, she will broaden her research and especially focus on solving the climate impact from the part of the animal production covering meat and milk production.

And there is plenty of work to be done within this field of research. Approximately 70% of the methane emission from agriculture in Europe originate from livestock, of which ruminants are responsible for 60%. A dairy cow discharges around 600 litres of methane daily when transforming the feed in the rumen. In total, it is estimated that ruminants are responsible for 3–4% of the global greenhouse gas emission. In EU, a demand has been made stating that the greenhouse gas emission from agriculture must be reduced by 30% before 2030 (compared to 2005), and in Denmark the required reduction is 39%.

“With this professorship, our department wants to strengthen an already strong team of researchers in the cattle area in order to maintain the scientific leadership and to strengthen research and innovation nationally as well as internationally for the purpose of ensuring healthy and climate-friendly animals”, says head of department Klaus Lønne Ingvartsen. He elaborates: “Farm animal production needs to solve some important climate and environmental challenges. It will take quantitative studies to understand, how biological processes from cellular to whole-body levels can be affected by nutrition and management, including how to identify and use new, functional feed ingredients. This is where I expect that we will benefit from Mette’s deep, physiological knowledge. Furthermore, we would like to draw on Mette’s long experience within teaching and supervision of students at bachelor’s, master’s and PhD levels and young researchers.

Keep the focus on the “ball” – not the cow!

The approach to the climate challenge for agriculture is clear for the newly-appointed professor: “Ruminants have kind of been proclaimed to be ‘climate criminals’. But we have to keep our focus on the ball when solving this problem – and the ball is not the cow but instead the greenhouse gas methane, which is formed by special microorganisms (archea) in the rumen of the ruminant animal”, says professor Mette Olaf Nielsen.


According to Mette Olaf Nielsen, there is a tendency in the climate debate to forget that ruminants play an important role when it comes to maintaining fertile farmland, as grass production and grazing prevent the decrease in soil fertility. At the same time, ruminants are efficient and necessary to conserve areas unsuitable for cultivation, which would otherwise grow into woodland and become overgrown with undesirable plant species. Moreover, ruminants are unique in transforming by-products, indigestible to humans, into high-quality food products for humans. Also in developing countries, small ruminants are unique tools for poverty alleviation and for value chain development based on high-quality foods in areas unsuitable for cultivation of crops.

Kvier på græs. Foto: Linda S. Sørensen, AU.


Grazing heifers. Photo: Linda S. Sørensen, AU.

Methane-mitigating methods must be fine tuned

Therefore, according to Mette Olaf Nielsen, we must solve the methane problem, and we must change our view on ruminants from being climate criminals to being recognised as providers of important societal services. “And we can actually do something to reduce the methane formation, but we need to fine tune the methods to do it”, says Mette Olaf Nielsen. She elaborates: “This is where my research area within ruminants’ production and lactation physiology plays a role, as this is the way we have to unravel how we can ‘adjust the knobs’ and find the sustainable solutions for reduction of greenhouse gas emission from the ruminants”.

The most recent and current research

During the past years, Mette Olaf Nielsen has researched a great deal within this field. Among other things, she has taken part in establishing a laboratory method at Department of Animal Science that simulate rumen fermentation. “This method can be used for screening of compounds/plants for anti-methanogenic properties and impact on feed degradability, before deciding which ones to try to feed to live cows. With new feed additives, it is very important to be able to document that they do not have unwanted effects in the cow’s body and on her normal physiological functions. It is also important to ensure that unwanted compounds do not accumulate in the cow’s tissue or milk, which is to be used for human consumption”, says Mette Olaf Nielsen.

In a current project, ClimateFeed, the potential of seaweed as a mean to reduce the methane production in the cows’ rumen is being examined. “Some of the seaweed species grown at our latitudes are able to reduce the formation of methane in laboratory experiments. Now, we have to identify the responsible bioactive components and their influence in the cow”, explains Mette Olaf Nielsen. The last part is part of a general effort to strengthen research to obtain a better understanding of the physiological processes underlying the formation of milk in the udder and the efficiency with which nutrients in feed is used for synthesis of milk and meat with the desired composition.

“Besides the research, I also look very much forward to using my long experience as a teacher at the University of Copenhagen to be involved in improving the education of Agrobiology and to increase the recruitment of students”, ends Mette Olaf Nielsen.

Professor Mette Olaf Nielsen

Born on 5 February 1960 in Frederiksberg.

Began to study agricultural science at the Royal Veterinary and Agricultural College (KVL) in 1983 after having graduated from Birkerød High school.

Graduated as cand.agro in 1983 from KVL.

Was granted a licentiate scholarship and graduated as lic.agro in 1986 from KVL based on a project regarding the physiological basis for growth hormones (somatotropins) stimulating effect on milk yield in ruminants.

Was employed as senior fellow, assistant professor and associate professor at KVL from 1986. When KVL was merged into the University of Copenhagen (KU), she was employed as PMSO and finally as professor in ruminant nutrition at KU until 2019.

In 2019, Mette decided to accept a temporary professorship in Production and Lactation Physiology in Ruminants at Aarhus University.

Since 1986, Mette has actively been involved in research projects and university cooperation in Bolivia and Cuba and is also adjunct professor at Universidad Central “Marta Abreu” de las Villas in Santa Clara, Cuba.

Today, Mette lives in Hvidovre and has three grown-up children.