Enlarge (credit: Hans Meleman | Getty Images)

It's an oppressively hot morning in the barnyard, even in the shade of the long open-air structure where the cows come to feed. On a typical farm, they would gather around a trough, but here at UC Davis they chow from special blue bins, which detect when and how much each one eats. It’s like Weight Watchers, only researchers here aren’t so much interested in these cows’ figures, but how much they burp.

Animal scientist Frank Mitloehner leads me to another kind of feeder, one that could easily be mistaken for a miniature wood chipper. He grabs a handful of the alfalfa pellets that the machine dispenses when it detects that a cow has poked its head in. “This is like candy to them,” Mitloehner says. I stick my head into the machine as Mitloehner points out a small metal tube within: “This probe measures the methane they exhale, and that happens every three hours for all the animals in this study.”

Enlarge / A natural gas flare from an offshore oil drilling rig in Cook Inlet, Alaska. (credit: Paul Souders | Getty Images )

The Environmental Protection Agency this week finalized a rule that kills off Obama-era limitations on how much methane, a potent greenhouse gas, oil and natural gas producers are allowed to emit into the atmosphere—even though industry leaders didn't want the changes.

The changes to the rules, known as the New Source Performance Standards (NSPS), remove some segments of the industry from being covered under the existing standards at all, and these changes also lift the methane caps on other segments, the EPA announced on Thursday.

The oil and gas industry basically splits into three big buckets of activity: upstream, meaning the actual drilling for oil or gas; midstream, which is the world of storage and pipelines; and downstream, that last mile where products are refined and sold. The current changes apply to the downstream and midstream segments, as the EPA broke down in a graphic ( PDF ).