2024 March Board Book

University of California researchers, including Ermias Kebreab and Matthias Hess, are using gene-editing technology to reduce greenhouse gas emissions of cattle by re-engineering their gut microbes Updated Jan 24, 2024

Given the scale of the beef and dairy industries, the central role they play in feeding people, and the diffculty of removing them from the economy, cattle clearly aren't moving on any time soon. For that reason, there's been no shortage of resources aimed at, quite literally, the gut of the emissions issue. As with most ruminants, cattle make the most of a paltry diet, converting cud, grains, and crop waste into muscle and milk. Extracting all that energy from cellulose and plant fbers requires the work of digestive microbes; cow rumens host entire colonies of bacteria, yeast, and fungi that ferment complex carbohydrates into microbial protein, which they then absorb, and volatile fatty acids, which they expel as methane and other gases. Several dietary supplements have been shown to minimize bovine bloating. A twice-daily garlic and citrus extract can cut emissions by 20 percent, while a red seaweed additive can inhibit them by as much as 80 percent without impacting animal health or productivity or imparting detectable favor to the resulting proteins. But having a transformative impact will require industrial-scale production and implementation. The promising strain of seaweed, for instance, prefers tropical waters, and developing a supply chain robust enough to serve tens of millions of cattle with a daily intervention leaves a trail of unanswered questions regarding effective farming, processing, and distribution techniques. Ultimately, tinkering with the animals' digestive system may hold the most scalable answer. Jennifer Doudna, who won the 2020 Nobel Prize in chemistry for pioneering the CRISPR gene-editing tool, is leading a University of California team that hopes to do just that. The recently launched project aims to identify the offending gut bacteria through metagenomics, another breakthrough technology that maps the functions of complex microbial communities, then restructure their DNA to produce less methane. The goal is to develop an oral treatment for calves that, once administered, will continue repopulating their rumen with the genetically modifed microfora.