WASHINGTON (AFP) - Giving one million dairy cows a growth hormone makes them produce more milk 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 in New York. 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...