Genetics can determine how much methane cows release when burping and passing gas, researcher says

Cows are responsible for about 40% of global methane emissions.  Methane is the gas passed or belched by the world's 1.4 billion cattle. In Scotland, cattle can be found grazing on the lush green pastures.  

Some environmentalists believe that when it comes to global warming, meat, especially beef, is among the worst foods that can be eaten. 

According to scientists, the methane cows belch out while turning feed into food is a far more powerful greenhouse gas than even the carbon dioxide produced by burning fossil fuels. 

Researchers at an experimental farm run by Scotland's Rural College believe that they have found a way to satisfy the world's ever-growing appetite for beef, while also producing less methane.Rainer Roehe, a professor of animal genetics and microbiome at the college, has been studying the digestive process in cows and has found that microbiome at the college, believes that one cow is not like another. He's found that the microbes in their stomachs not only vary from cow to cow, they determine how much methane the cow produces. 

"There are huge variations in the stomach," Roehe told CBS News correspondent Mark Phillips.  

Cows have four stomachs and don't digest what they eat — the bugs in their gut do. Their food mixes with a kind of microbe soup in the rumen, or first stomach, and is then re-chewed, before passing through the rest of the system. 

Roehe's work shows that genetics can predict which animals will have the right microbe cocktail to produce the least methane. In other words, you can breed low-methane-producing cattle. 

"We are predicting that we reduce methane by 50%," Roehe said. 

How does he know this? He measures it. The cows are put in hermetically sealed chambers on the farm for three days and I the gases they emit are analyzed.

Producing methane is considered a waste of energy for a cow. The less they produce, the more efficient they are at turning cattle feed into human food.  

According to Oxford University's Joseph Poore, judged against the nutrition it provides, beef is simply too environmentally expensive and found that a 50% reduction in greenhouse gas production is different from a 100% reduction, which is what we would get if people stopped eating meat.

"Beef provides about 6% of our protein and 2% of the global calorie, worldwide," Poore said. "If you look at the environmental impacts, beef is about 30% of our greenhouse foods greenhouse gas emissions, so you got a massive imbalance between the kind of environmental impacts of this product and the nutrition it provides."

In In the rugged terrain of the Scottish highlands, Cattle raising is arguably the most efficient food-producing use to which these fields can be put because nothing much will grow there other than grass. There are lots of other areas of the world like that. As with so much of the environmental argument, there is a lot to chew over.