AG2PI Field Day #24 - February 8, 2023

Omics Tools to Mitigate Enteric Methane Emissions from Dairy Cattle

There is a critical need to develop new practices and technologies that enable a sustainable decrease in enteric methane emissions from dairy cattle. Selective breeding is one of the strategies to achieve permanent and cost-effective reductions in methane emissions. This seminar will present some of the challenges and opportunities in this field, including phenotyping, trait definition, the development of a reference population, the use of milk mid-infrared spectra as a non-invasive approach, and the manipulation of the rumen microbiome.

Presenter

Francisco Peñagaricano is Assistant Professor at the Department of Animal and Dairy Sciences, University of Wisconsin-Madison. His research program focuses on developing and applying methods to dissect the genetic basis of relevant traits in dairy cattle. His research involves gene mapping, genomic prediction, multi-omics data integration, and network modeling.

Mitigation of Enteric Methane Emissions through Nutritional Intervention

Ruminant livestock are an important source of anthropogenic methane. Research in the area of enteric methane mitigation has grown exponentially in the last 2 decades, with various strategies for enteric methane abatement being investigated. The talk will address strategies including production intensification, dietary manipulation such as supplementation and processing of concentrates and lipids, and management of forage and pastures, and rumen manipulation (supplementation of ionophores, 3-nitrooxypropanol, macroalgae, alternative electron acceptors, and phytochemicals).

Presenter

Ermias Kebreab is Associate Dean and Sesnon Endowed Chair in Sustainable Agriculture at the University of California, Davis. He conducts research in animal nutrition, mathematical modeling of biological systems and impact of livestock on the environment.

Chat Questions

If this is a genomic comparison, it sounds like a HUGE quantity of data - what is the speaker's data management plan?

Yes, we have a data management plan in place to handle phenotypes, genotypes, and sequence (microbiome) data.

Is there any data on how reducing methanogenic bacteria in the rumen will impact overall cattle health and production indicators?

Some diet interventions may have negative impacts. Now, through genomics, selective breeding, and the use of selection indices, we can consider potential negative correlations.

Can metabolomics be used in determining amount of methane emissions and mitigation?

We plan to use metabolomics to better understand the rumen microbiome of low vs high methane emissions cows. Let's see if we can use this info later for prediction!

Is the SEM or DAG for the intervention known? Any references?

Yes, I think the DAG is somehow known: CH4 ← Genome → Microbiome → CH4

What weight will be put on methane emission in the selection index?

Great question, the million-dollar question! Honestly, we don't know yet.

What do you think about using milk fatty acids for large-scale methane prediction? Is this feasible?

If fatty acids in milk are calculated based on milk spectra, then using spectral data directly to predict CH4 emissions is probably a better approach, i.e. we will not gain much by using the fatty acids derived from the spectra.

Were you only looking at genetic selection as a stand-alone factor to mitigate methane emission? what about feed quality and feed efficiency?

No! we will need to combine multiple strategies, including selective breeding and nutritional interventions.

Do you foresee to standardize your spectra for CH4 prediction across the US and the different labs? And if yes how?

Most of our spectra data come from the same lab, same technology. We have a few farms that use a different lab. Milk labs across US standardize/reevaluate their protocols frequently.

In terms of the management recommendations you showed for forages, do you have data about warm-season and, specially, tropical grasses with high levels of NDF, low WSC, low CP, and low DM and NDF digestibilities?

Unfortunately I do not have data. These types of data are hard to come by but necessary to do meta-analyses on. The closest I came was using a mechanistic model and see various interactions that affect emissions.

Any idea on promoting other hydrogen sinks in the rumen like acetogens?

Acetogens are thermodynamically outcompeted by methanogens. So the idea is to knock out some genes on methanogens which will give advantage to acetogens and other hydrogen utilizing microbes.

Contributions from the Audience

• Lactanet Canada will publish official genomic breeding values for methane via the methodology presented in Shadpour et al. in April of this year.
• Farming seaweed at large scale will have additional impacts (GHG and others*. Life cycle assessment would be helpful here as well.
• Bromoform emissions leads to ozone depletion for instance. Hopefully, not that significantly (see https://doi.org/10.5194/acp-22-7631-2022)