"People have long looked into reducing this enigmatic protein, or completely knocking it out, because there has been no definitive function assigned to it. So, we developed this scientific model to investigate the effect of knocking BLG protein out on the composition and functional properties of milk, and to determine whether the absence of BLG produces cow's milk that is hypo-allergenic," said Dr Wagner. "This is the real discovery component to this project, and Daisy provides us with the opportunity to answer a lot of those questions."

He added that to avoid the delay of two years before a natural lactation, the milk analysed was from an induced lactation. "We only obtained small quantities over a few days for these initial studies. We now want to breed from Daisy and determine the milk composition and yield from a natural lactation. We also want to investigate the origin of Daisy's taillessness, a rare congenital disease in cows," he said.

Malaghan Institute Director Prof Graham le Gros said, "This outstanding breakthrough has enormous implications due to its potential to reduce the significant impact milk allergies have on our children and neatly avoids the concerns associated with genetic modification of the milk proteins themselves."

Dr Wagner said in future, the basic process of using designer microRNAs to target other genes could provide an efficient tool to change additional livestock traits, for example to produce animals with enhanced disease resistance and/or improved lactation performance.

The successful research team comprised co-authors Anower Jabed, Stefan Wagner, Judi McCracken, David Wells and Goetz Laible. The work was funded by the New Zealand Ministry of Business, Innovation and Employment and AgResearch.

"This is tremendously significant," said Dr Tom Richardson, chief executive of AgResearch. "PNAS is one of the top journals in the world, and to be published in it reflects the world-leading quality of the science behind this discovery. This will be one of the top-ranking science publications from New Zealand this year."