GIVING one million dairy cows a growth hormone makes them produce more milk and would cut greenhouse gas emissions equal to taking 400,000 cars off the road, a US study found.

Large scale cow milk production requires the use of huge amounts of land, water and feed resources, noted Judith Capper, a researcher at Cornell University.

But using rbST -- the first biotech product used on US farms which has been in farm use for about 15 years -- can help reduce the "carbon hoofprint" while still meeting dairy demand, she explained.

Known as either recombinant bovine somatotropin (rBST), recombinant bovine growth hormone (rBGH), or artificial growth hormone, the hormone has been used in the US for over a decade to boost milk production.

But use of the hormone is highly controversial. It has been banned by the EU which cited animal health concerns. The product also has emerged in some places as a symbol of big corporate interests undercutting a traditional small farmer's product.
"Giving rbST to one million cows would enable the same amount of milk to be produced using 157,000 fewer cows. The nutrient savings would be 491,000 tonnes of corn, 158,000 tonnes of soybeans, and total feed would be reduced by 2,300,000 tonnes. Producers could reduce cropland use by 219,000ha and reduce 2.3 million tonnes of soil erosion annually," researchers said in a statement.

Their work appeared in the Proceedings of the National Academy of Sciences recently.

Cattle-raising is the source of 37 per cent of methane released by human activity largely as a byproduct of animals' digestive systems and 64 per cent of the ammonia that contributes to acid rain.

Cattle-raising worldwide produces more greenhouse gases than vehicle traffic, the same FAO report found.

It said that while cattle-raising represents nine per cent of CO2 from human activities, it nonetheless yields a larger part of the more toxic gases among greenhouse gases, such as sulfur dioxide. -- AFP