According to the Food and Agriculture Organization, livestock are responsible for 18% of global greenhouse gas emissions, most notably, the emission of methane, whose greenhouse warming effect is 25 times stronger than that of carbon dioxide. One potential solution lies with the naturally occurring antioxidant melatonin. In both lab tests and practical application, researchers recently showed that melatonin treatment significantly reduced methane production in cows, reducing methane emission from their respiration by approximately 50%. This is due to melatonin's ability to alter the microbial composition of the rumen. Melatonin lowers volatile fatty acids production, which reduces available material for methane synthesis. Melatonin also reduces the abundance of Methanobacteria, microbes responsible for generating methane. Interestingly, while methane and fatty acids were lowered, neither did the cows consume less food nor did their nutrition seem to be affected. In fact, melatonin treatment even led to increased milk lipid and protein content versus control cows, indicating a potentially beneficial side effect. While the exact mechanisms still need to be explored, it’s clear that melatonin can influence the gut microbiota of cows in beneficial ways. This discovery could support efforts toward low-carbon dairy farming and reduce the greenhouse impact from methane emissions.