Researchers in New Zealand have genetically engineered a cow to produce milk with very little of a protein that causes an allergic reaction in some children. They hope the technique, which uses a process called RNA interference that reduces the activity of certain genes without eliminating it completely, can be used to control other traits in livestock. With mothers breastfeeding less, cows’ milk is an increasing source of protein for babies, but the different composition of cows’ milk can cause an allergic reaction. He said that although RNA interference has been shown to work in manipulating plants and worms, “it has not worked in livestock before”. Whitelaw said that aside from accentuating or reducing genetically determined characteristics in farm animals, such as growth rate, the technique could be used to improve defense against infection. “Time will tell how widely applicable RNA interference will be in GM livestock. But this is certainly a milestone study in this field,” he said.
