90% of the methane produced by cows is from eructation not flatulence, according to AGU Blogosphere:
This may come as a surprise, but 90 percent of cow methane comes from their front ends. Octavio Castelán-Ortega measured that in an experiment he and others conducted in Mexico. He works at the Autonomous University of Mexico State in Toluca, near Mexico City.
Castelán-Ortega, a veterinarian, and Luisa Molina, an atmospheric scientist, monitored the respiration of cows and found steep reductions in methane when cows were fed a diet enhanced with certain plants. They presented their results in an eye-catching poster (featuring a cow with its head in a chamber that resembled a voting booth) at the recent fall meeting of the American Geophysical Union in San Francisco.
In a study at four sites in Mexico, Castelán-Ortega and Molina found cows that fed on grasses mixed with the leaves of delicate tropical leucaena trees belched about 36 percent less methane than those on a straight grass diet. The cosmos flower, with the Latin name Cosmos bipinnatus, reduced methane emissions 26 percent when it was added to feed.
The diet including leucaena tree leaves also improved the cows’ milk production. Both plants contain bacteria-killing tannins that disrupt fermentation without interfering with a cow’s digestion. Too much of the plants would be toxic, but a small proportion seems to be beneficial. We drink tannins all the time. They are the bitter compounds in coffee and tea.
I wonder about the impact on the flavor of the milk.
This will have an effect on the new California law restricting the methane gas from cows.
If there were a law in California (or Illinois) restricting emissions from politicians, we’d be getting somewhere. They don’t call Chicago “the Windy City” because of the weather, you know.