Author: Derek Yang
Editors: Elizabeth Li, Louis Li
Artist: Jenny Luo
Methane produced by cows is mainly a product of digestion, which also largely contributes to the concentration of greenhouse gases around the globe and therefore to the enhanced climatic change. Due to its ruminant nature, the cow has complex gut microbes breaking down fibrous plants in a process called enteric fermentation. In this process, methane is emitted, which is expelled from the cow's body primarily through belching. Estimating that a single cow yields about 220 pounds of methane a year and that there are over a billion cattle in the world, most would say that a reduction in this may be one of the biggest ways to cool down globally. Then, could genetic modification come into play?
The idea behind engineering cows to produce less methane finds its roots in the modification of the gut microbiome or physiology in cows in such a way that it suppresses the production of methane. The first chamber of a cow's stomach, the rumen, houses microbes that help fermentation. Among these, the methanogens are the microbes that undertake methane production. Scientists have been trying to reduce methane production from these methanogens without affecting the cow's efficiency in digesting its food. Genetic modification of the rumen microbiome could be one of the more efficient ways. Researchers are currently working on adding or enhancing non-methanogenic microbes that can compete with methanogens for hydrogen and feed on it, therefore, preventing methane synthesis. Such microbes, including sulfate-reducing bacteria, can reutilize hydrogen not for methane production but for producing fewer harmless by-products. These are early days in this field, and although initial results from this work look promising, such engineered microbial populations will need to be maintained in a very dynamic ecosystem of the rumen.
The second approach is to modify the genes of cows in order to affect their digestion process. The development of gene-editing technologies, such as CRISPR, would theoretically allow for editing of the genome of a cow, either to prevent methanogens from efficiently synthesizing methane or to synthesize enzymes impeding methane production. CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) is a genetic editing tool that allows scientists to modify specific genomes within an organism. For example, CRISPR can be used to alter cows’ genomes to suppress their methanogen activity or enhance the production of enzymes that inhibit methane synthesis. While these ideas are promising, they are still being experimented on, not to mention the ethical and regulatory concerns and issues of public acceptance of this technology.
In addition to genetic engineering, researchers are also exploring other methods to reduce methane emissions like feed additives. Compounds such as 3-NOP added to cattle feed have been shown to inhibit the action of enzymes used by methanogens in methane production. Genetic manipulation of the cow to better metabolize or respond to such additives can further improve the suppression.
Less gassy engineering cows have their challenges and risks too. However, it also emerges that genetic interventions at the microbiome or organism level must be weighed against such unintended effects as reduced digestion efficiency, health problems, and ecological impacts in cases where genes eventually flow into other organisms. Methane mitigation strategies need to be discussed in the context of socio-economic issues related to cattle farming. This will further exacerbate inequities within agriculture because small-scale farmers, especially those in developing countries, cannot access these highly expensive genetic technologies.
While genetic engineering itself cannot solve the negative impact of livestock farming, it is certainly a creative solution. Combinations of genetic modification, feed additives, better grazing practices, and dietary changes could collectively bring down methane from cattle. Further research into strategies is gaining traction amidst the growing urgency for food production to match up with climate goals.
Genetic modification of cows to produce less methane would eventually be a sure step towards making agriculture more ecologically sustainable. As technology progresses, a collaboration by scientists, policymakers, and farmers will be paramount in ensuring that solutions are not only effective but also fair and ethical in finding a way out of some of the intractable ecological challenges facing agriculture today.
Citations:
Nickel, Rod. “The Climate-Friendly Cows Bred to Belch Less Methane | Reuters.” Reuters, 8
Quinton, Amy M. “CAN CRISPR Cut Methane Emissions from Cow Guts?” UC Davis, The
Regents of the University of California, Davis campus, 25 Apr. 2023,
Wait, Liana F. “Could We Breed Cows That Emit Less Methane?” Penn Today, University of
Pennsylvania, 2 Aug. 2023, penntoday.upenn.edu/news/penn-vet-could-we-breed-
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