In scientific dialogue, feeding and breeding experts deliberate on the possibilities for, and the challenges involved in, reducing methane formation in cattle
(GfE). With four contributions, particular weight was attached to this topic during the workshop entitled 'Reducing methane losses in cattle through feeding and breeding?' which was conducted at the 75th annual conference of the GfE (Society of Nutrition Physiology). This took place against the backdrop of criticism being levelled at ruminant animals for their extensive involvement in emitting gases such as methane that harm the climate.
In biological terms, methane formation in cattle is the result of long and extraordinarily effective evolutionary development. Only this evolution has enabled cattle and other ruminant animals to obtain nourishment from plants that man and other animals are unable to utilise. This particularly includes structural carbohydrates (fibrous materials) from grass, for instance, or generally from coarse feeds, thus giving access to significant amounts of resources for the food chain. For the ruminant, however, the emission of methane equates to energy loss with an environmental impact. Advanced feeding and breeding methods could help to defuse this conflict of objectives in the future.
The GfE would like to point out that this topic is already being addressed intensively, but that many questions remain unanswered or have not yet been dealt with scientifically.
The workshop tackled the following questions:
Dr Björn Kuhla (Institute of Nutritional Physiology, Leibniz Institute for Farm Animal Biology, Dummerstorf) first outlined the 'Fundamentals of ruminal methane production, their importance to the greenhouse effect and natural limits of methane reduction'. In detail, he noted that ruminant animals should not be deemed climate killers due to their quantitative contribution to global greenhouse gas emissions, which amounts to less than 5 percent of total emissions. Nevertheless, ruminants' share of emissions could be reduced by over 30 percent by implementing various approaches. However, a combination of measures aimed at optimised feeding to maintain the animals' health and simultaneously bring about a reduction in methane emissions and increased carbon sequestration in the soil promises to be more effective and aspirational. The latter can be backed-up with intelligent pasture grazing concepts.
Very promising options for 'Using mid-infrared spectra (MIR) of milk to estimate the methane emission of cows' were presented by Prof. Nicolas Gengler (Gembloux Agro-Bio Tech, University of Liege, Belgium). MIR spectra are already being used routinely, repeatably and on a large scale to assess the composition of milk but also to estimate methane emissions. In the long term, management and breeding could benefit significantly from reliable information concerning the methane emissions of individual animals. The prerequisites for this are the standardisation of MIR spectra evaluation and the guaranteed applicability of the equations for estimating the methane values when using feed additives that influence methane formation in the forestomach.
Prof. Hermann H. Swalve (Institute of Agricultural and Nutritional Sciences, Martin Luther University Halle-Wittenberg, Halle/Saale) reported on the 'Role of genetics in methane emission in cattle'. Here, focus was placed on the genetic influences of the host on the microbiome of the rumen. The variation in methane emissions with identical feeding and performance is determined genetically in part; measuring methane emissions in individual animals is very complex. One approach being pursued successfully is 'laser methane measurement' in the cow's respiratory air; the definition of specific measures is currently under discussion. Economic aspects and correlations with other characteristics also have to be taken into consideration in this. Essentially, investigation is also required to determine whether the microbiome has to be dealt with more intensively by breeders and which breeding strategy promises the greatest success.
In the fourth contribution, Prof. Michael Kreuzer (Institute of Agricultural Sciences, Eidgenössische Technische Hochschule, Zurich, Switzerland) dealt with the possible measures for 'Controlling methane emission through feeding'. The list of measures to be included in the 'toolbox' for reducing methane appears to be relatively extensive, and their efficiency, price and side effects, particularly on performance, vary widely. It is therefore also unlikely that there is or will be just one measure that is equally suitable for all farms. Individual reduction measures also need to be examined as regards their effects on other emissions such as nitrogen (e.g. nitrous oxide, ammonia or nitrate). Some products are effective against more than one type of emission (e.g. tannins), whereas others are not (e.g. lipids). On the whole, it is advisable to also analyse the rapid implementation of the measures for animal production systems in the light of the significantly shorter half-life of methane in the atmosphere compared to that of carbon dioxide in order to achieve correspondingly quick effects on or against global warming.
The individual contributions were published in the proceedings of the 75th annual conference of the GfE (16 to 18 March 2021).
They can be purchased online from: https://www.dlg-verlag.de/shop/proceedings-of-the-society-of-nutrition-physiology-band-30.html.
Further information about the GfE is available at www.gfe-frankfurt.de.