British researchers have begun a $1.5 million government research program to propose ways to change cows' diets in order to reduce methane production by feeding them grasses with higher levels of sugar, which facilitate digestion. "These grasses present a better balance of nutrients to the microbial population in the rumen and are used more efficiently," says Prof. Mike Theodorou, head of the UK's Science Development at the Institute of Grassland and Environmental Research in Aberystwyth. "In doing so, more of the ingested carbon and nitrogen will be converted to meat, milk, hide, and wool."
The scientists are investigating how such plants can be bred to contain even higher sugar content and to grow more abundantly on pastureland.
Other researchers suggest adding certain plant ingredients to livestock menus. Michael Kreuzer, head of the Swiss Ruminant Nutrition Group in the Institute of Animal Science of ETH Zurich, proposes adding extra fat (from coconuts, crushed flaxseed, or sunflower seed), as well as extracts rich in tannins and saponins (already available in powdered form).
Unlike antibiotics, these plant-based additives seem to have no secondary effects on milk or meat. And "measurements showed that by using them it's possible to reduce the emission of methane up to 20 percent," Professor Kreuzer says. In order to control the cows' exhalations, he puts them in respiration chambers for 48 hours, feeds them, and measures the concentration of methane from the chamber every few minutes.
The animals aren't always amused. They are not used to eating more fats. Moreover, saponins taste soapy, and tannins are bitter. For the cow, tannin is like drinking a cup of black tea, Kreuzer says: "The more you put into their feed, the merrier it is, but the more awful it tastes."