Feeding cows seaweed could slash global greenhouse gas emissions

The mechanism seems to be that this seaweed contains bromoform (known as tribromomethane to the squares):

https://www.ncbi.nlm.nih.gov/pubmed/27009670

And bromoform poisons methanogenic bacteria:

https://www.ncbi.nlm.nih.gov/pubmed/22059589

Given that bromoform is the same shape as methane but with a monster dipole because of the electronegative bromines, i assume it's a straightforward active site inhibitor. Oldest trick in the book.

The methanogenic bacteria consume hydrogen and CO2 to make methane, so with them inhibited, there's just more hydrogen and CO2 in the gut. It shouldn't make a massive difference to the animal, except there are three times as many gas molecules, so presumably they burp more often.

Would be interesting to know where the material ends up, if it's not being emitted as methane. Does it contribute to the animal's solid waste? If so, how does the breakdown of that waste compare with the original methane problem, e.g. does it contribute to CO2 emission, similar to if the methane was collected and burned? (Each methane molecule contributes more to the greenhouse effect than a CO2 molecule, so this would still be a net win)

I am curious if there is a measurable benefit to the animal? If there is so much methane not being produced is it because the current diet is just so wrong for the animal that the methane is the adverse reaction to it? Does cattle that is allowed to graze as it likes with no added foods producing the same amounts?

Also, what is being produced if anything if the methane isn't? As before, is this beneficial or not to the animal.