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. "In developed countries, 2-3 percent of infants are allergic to cows' milk proteins in the ﬁrst year of life," the researchers said in a paper published in the Proceedings of the National Academy of Sciences. Anower Jabed and colleagues at the New Zealand government-run AgResearch company said their genetically modified cow produced milk with a 96 percent reduction in the protein beta-lactoglobulin (BLG), a component known to cause allergic reactions. 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. Another gene manipulation technique using a process called homologous recombination could theoretically knock out, rather than suppress, the gene that produces BLG but the researchers said that, so far, this has not worked.
Bruce Whitelaw, professor of animal biotechnology at the University of Edinburgh, said the New Zealand research "offers a good example of how these technologies can be used to provide alternative strategies to current manufacturing process". "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.