It is possible to improve the feed efficiency of dairy cattle and reduce their methane emissions at the same time, making both the climate and the farmer’s economy winners. This can be done using low-cost, high-capacity recording methods that are already available, according to a group of researchers, some of whom are from Aarhus University, in an article in the scientific journal Animal.   

Both feed efficiency and methane emissions are heritable traits in cows. Both traits are to a certain extent influenced by the cow’s microbiome, which is to say the composition of microorganisms found in the rumen and which help the cow digest grass and other cellulose-rich feedstuffs. 

By reviewing the literature, the research team ascertained that there is an apparent positive correlation between the amount of methane emitted per kg milk produced and the cow’s feed efficiency. The correlation is not simple, and a large part of it is due to a dilution of the maintenance requirement on a large dairy cow operation, while the opposite effect can be a slightly lower digestibility in efficient cows. All told, it seems that feed-efficient cows emit less methane per kg milk than less feed-efficient cows. 

Systematic recording is necessary

A large-scale systematic recording of feed intake and methane emission is required to carry out an in-depth analysis of data. 

- The costs of systematic recording of feed intake and methane emission has hampered data analysis for large cohorts, says Senior Researcher Peter Løvendahl from the Department of Molecular Biology and Genetics at Aarhus University and leading author of the scientific article.    

In their review of the literature, the researchers compared various methods for expressing feed efficiency and methane emission. The researchers thus found that it is necessary to measure feed uptake and related traits – not least body weight and body condition – quite accurately in order to obtain a correct assessment of feed efficiency.   

- It is possible that you can attain sufficient accuracy for breeding value estimates by just measuring feed uptake over short periods, says Peter Løvendahl.    

The researchers also found that methane emission should be measured under practical conditions on commercial farms. Emissions can be assessed accurately using relatively cheap high-capacity instruments. 

Rumen microflora plays a double role

The rumen’s microflora plays a double role in cow digestion. The microflora is important with regard to metabolising cellulose-rich feedstuffs and liberating essential nutrients to the benefit of the cow. On the other hand, the rumen microflora produce methane as part of their digestive process. Methane is a potent greenhouse gas.  

There are clear indications that there is an interaction between the cow and its rumen microflora. Both the cow, its microflora and the interaction between the two show genetic variability and correlation, so it is possible to select for these traits.   

When the cow burps methane, she also loses energy. By reducing the amount of methane (CH₄) emitted, there should theoretically be more energy left over for milk production.   

- More studies are required to shed light on the possibilities and potential of this, says Peter Løvendahl. 

For more information please contact

Senior Researcher Peter Løvendahl, Department of Molecular Biology and Genetics, email: peter.lovendahl@mbg.au.dk, telephone: +45 8715 7495, mobile: +45 4055 3992