Cow-belching study aims to cut methane

TOKYO — Researchers have stumbled on a way to stop cows from emitting methane — a potent greenhouse gas — when they belch, a finding that could help the fight against global warming.

Methane generated when livestock belch while eating is said to account for about 5 percent of global greenhouse-gas emissions. But supplementing the animals' diet with cysteine, a type of amino acid, and nitrate can reduce the methane produced by the animals, according to the researchers.

Methane is generated in the stomachs of ruminants, such as cows and sheep, as bacteria break down plant fibers. The gas is emitted into the atmosphere when the animals belch as they chew cud.

The research team at Obihiro University of Agriculture and Veterinary Medicine in Hokkaido, headed by professor Junichi Takahashi, initially noticed that dairy cattle that consume a large amount of nitrate from grass growing in soil doused with high levels of chemical fertilizer release only traces of methane when they belch.

The researchers stumbled on the relationship between nitrate and methane generation when they studied a mass poisoning outbreak among a herd of cows.

The team found that feeding the animals cysteine in addition to nitrate not only significantly cut the methane they generate but also helped prevent them from being poisoned.

The study also showed the nitrate does not affect milk quality. The amount of cysteine a cow needs each day costs about 95 cents, according to the researchers.

The university team has obtained a patent for the technique in Japan, the United States, Australia and two other countries.