GM cow produces non-allergic milk

In what could be a good news for several Indian children who avoided cow’s milk for its allergic effects, scientists have now engineered a genetically modified cow that could produce milk without its allergy-causing component.

Milk from the GM calf is rich in casein that increases calcium levels, while dairy industry could find the high cheese yields commercially beneficial.

Casein is milk's main protein, which is responsible for its goodness.

A team of researchers in New Zealand created the genetically engineered female calf that would produce milk containing high levels of protein and a dramatic reduction in the levels of beta-lactoglobulin (BLG) -- a whey component known to cause allergic reactions in human -- compared with non-engineered calves.

BLG is dispensable for milk without greatly altering its properties.

“The same milk quality (or even close to it) can not be achieved through conventional hybrid cows,” Warren McNabb, director of research at AgResearch, a biotech company in New Zealand, told Deccan Herald.

The ten-month old calf, which was born without a tail, was artificially induced to produce milk. scientists are now waiting for the natural lactation cycle to see if it produces high casein and low BLG milk naturally.

Published in the Proceedings of National Academy of Sciences on Tuesday, the study demonstrate how tweaking genetic make-up of cattle can be an effective strategy for altering milk composition and other livestock traits.

The strategy adopted is known as RNA interference which moderates the activity of genes responsible for producing the whey protein.

The scientists claim it is better than completely knocking out the BLG gene or taking recourse to processing technologies to reduce the BLG level.

“We generate a transgenic calf whose milk contained no detectable BLG and more than twice the amount of casein milk protein,” the team comprising researchers from AgResearch and University of Waikato reported.

Even though there is no systemic study to know the extent of milk allergy prevalence in India, a 2009 study carried out on children in a Lucknow hospital found that cow milk intolerance was not uncommon in India.

The team found 40 cases of milk intolerance among children who were admitted with chronic diarrhoea between June 2004 and December 2007.

Milk were successfully restarted only on 25 children after keeping them on milk free diet for 15 months, according to the study published in the Journal of Gastoenterology and Hepatology in October, 2009.

Scientists first tested the process in a mouse model engineered to mimic the mammary gland of a sheep, which resulted in a 96 per cent reduction of BLG.