Here is the product web page:
https://www.dsm.com/anh/products-and-services/products/methane-inhibitors/bovaer.html
Doesn’t really say what’s in it.
“HOCH2CH2CH2ONO2”
Wiki
3-Nitrooxypropanol (abbreviated as 3-NOP or 3NOP) is a synthetic organic compound with the formula HOCH2CH2CH2ONO2.[1] It is the mononitrate ester of 1,3-propanediol and acts as an enzyme inhibitor that specifically targets methyl coenzyme M reductase (MCR), the enzyme that catalyzes the final step of methanogenesis in the digestive system of ruminants, such as cows and sheep.
https://en.wikipedia.org/wiki/3-Nitrooxypropanol