Well, we could just give the animals bromoform directly.
I wonder whether chlorinating their water supplies (perhaps with humic acid addition? Someone help me on the chemistry!) would have a significant effect.
You'd have to be VERY careful with that. Chlorine promotes formation of tri-halomethanes (chloroform)en vitea and other potentially harmful chemicals in the water itself such as dioxin and PCB.
Chloroform and those other chemicals are all linked statistically with an elevated risk of various types of cancer. Maybe the cows or their owners won't care about that but then, the change in their metabolism might carry over into their products (meat, milk).
That's one reason that whenever possible it's probably better to drink water that has had most of the chlorine removed by filtering.
It's also probably a good idea to obtain information about the likely biochemical/physiological consequences of changing what cows might ingest from a scientist who does not have a vested political or corporate interest, such as someone who is employed by a chlorine manufacturer or is beholden to any political party for funding their livelihood with research-grant money.
Ecoparanoids / far leftists are notorious for trying to force changes that fit their political template without doing enough research into the possible unforeseen consequences of their actions. They have already done untold damage to the economies of European nations and some U.S. states (like Mexifornia, New York, New Jersey, West Virginia and others) by forcing their reckless paranoia down the throats of a credulous, uninformed or apathetic population under pretext of "stopping climate change" PTUI!
I should probably also point out that I'm most definitely NOT accusing Suppressed of having that motivation, 'just responding substantively to the suggestion he raised.