BOVAER. Should you be worried? In short: no. Let me explain... Firstly, wtf is it? It's classified as a "feed additive". The active ingredient is something called 3-nitrooxypropanol (3-NOP). Chemically, this is a primary alcohol (similar to ethanol) and a molecule of organic nitrate stuck together. Stick with me because it gets interesting... So this 3-NOP stuff stops a very specific enzymatic reaction in the cows rumen (the largest part of it's stomach). See the image. Everything you see in the image is what normally happens. 3-NOP enzymatically blocks ONLY the last step to prevent methane forming. What happens instead is the cow produces something called NOPA -> then HPA -> then eventually lactose and carbon dioxide. We know this because some (thankfully) paranoid scientists radioactively labelled some 3-NOP, fed it to cows, goats and rats and followed what happens all the way to the end. From this experiment they also figured out that zero detectable 3-NOP ends up in the milk or meat. Link to that study: sciencedirect.com/science/ar… A separate study also did NOT find any 3-NOP ended up in the milk but the milk did have 21% more vitamin B12. This is probably because the cows stomach produced more microbobes that make B12. Link: sciencedirect.com/science/ar… So back to the question, should you be worried? Personally I don't see anything to be worried about here. None at all. That doesn't mean I think cows are burning the planet nor do I like the idea of the food supply being tampered with. That said I am happy this isn't gene editing and this isn't pumping cows with pharmaceutical drugs. I'm also happy I can continue enjoying my steak and butter. P.S. all the health warnings you're seeing about 3-NOP irritating the skin etc is because it's made with a primary alcohol. Pure ethanol does all the same stuff if you handle it directly.