Living the Scientific Life (Scientist, Interrupted)

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To meet the demands of the health-conscious consumer, how about developing cows that produce skim milk? Well, scientists have identified a cow that does this, and they hope to establish herds of the animals to meet the increased health demands from the public. The cows, which carry a particular genetic mutation, were bred from a single female, named Marge, who was discovered by researchers when they screened milk from millions of cattle in New Zealand.

“Marge looks like an ordinary Friesian cow but has three key differences. She produces a normal level of protein in her milk but substantially less fat, and the fat she does produce has much more unsaturated fat. She also produces milk with very high levels of omega3 oils,” said Russell Snell, the chief scientist at the biotech firm, ViaLactia.

Omega3 oils are sometimes thought to improve brain power, and the saturated fats that are normally found in cows’ milk are linked to increased risk of heart disease. Marge and her daughters produce milk with less than 1% fat. Additionally, because these cows’ milk contains so many unsaturated fats, butter made from these cows’ milk is spreadable straight from the fridge, like margarine.

Marge was discovered in 2001 and ViaLactia’s researchers bought her for £120 and moved her to a secret location. Even though they now owned Marge, the important issue was whether Marge’s calves would inherit her unique traits.

“You have to generate daughters and then they have to carry a calf and deliver milk,” said Snell. “The eureka moment was when we found her daughters produced milk like their mother.”

ViaLactia hopes Marge’s male offspring carry the same genes as her daughters. “To have a bull from Marge’s offspring who passes on her traits would be the holy grail. It would allow us to reproduce hundreds of thousands of cows like Marge,” said Snell.

Scientists are still trying to identify the genes that give Marge her special traits. Helen Wallace, of GeneWatch, the genetics watchdog, said it was important to ensure the mutations that produced the milk were not harmful in any way. “If so then using such animals would be far better than creating genetically modified cows.”

Cited story.


  1. #1 Aaron Boyden
    May 27, 2007

    Is there any way other than public relations in which it would be better to use a mutant cow than a genetically modified cow?

  2. #2 The Ridger
    May 27, 2007

    I remember back in the early 70s when I was studying animal husbandry (I’ve heard the jokes, thanks) in college (not what I ended up doing professionally), they taught us that many Holstein-Friesans produced milk with too little fat to be sold as whole milk. It wasn’t skim, but I always figured they could breed for that if they really wanted to.

  3. #3 Bob O'H
    May 28, 2007

    Aaron – my guess is that it would probably take much longer to develop. I don’t know how much is known about the genetics of fat production, but it might be that several genes are involved. In that case, you would have to sequence them all, and then transform them all into the cow.

    It’s also not clear if this cow is a mutant. It could be that she was either bred as a low fat cow, or the company screened a lot of cows, and took the one with the lowest amount of fat. If it’s the latter, then her offspring will almost certainly produce more fat.


  4. #4 David Harmon
    May 28, 2007

    Aaron: Mostly, that the mutant is already there, testably healthy and now proven to be heritable. If we set out to engineer something, we’d need to get past all the usual survival hurdles, hope we hit the right genes, and then do all the same testing anyway.

    Basically, this is how humans have been doing genetic engineering, since millennia before Darwin, let alone Watson&Crick. Was it last year that the spotlight was on those uber-muscled cows? This year I guess it’ll be the skim-milk cows.

    (Bah, the & preview bug is still around…)

  5. #5 Jenny F. Scientist
    May 28, 2007

    ‘Mutant’ generally is used in genetics to mean ‘not of the prevalent genotype among the population’. (This is an admittedly fuzzy definition, but that’s how it is.) So this cow IS a mutant, the same way that irradiating bacteria (or seeds, or whatever) produces mutations, i.e. gene variations.

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