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Author Topic: How does a cow produce milk on a diet of grass and water without it being contaminated by it's intestines?  (Read 443 times)

Offline thedoc

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Mohammed Laher  asked the Naked Scientists:
   Good day. A Cow eats  grass and drinks water and producers pure wholesome milk and it resides  in the body close to the  the intestines and yet the smell does not penetrate it. Man with all his achievements og being able to fly into space cannot produce fresh milk with these gradients ,it has been attempted since1921 yet  we still awaitMakes you think doesn't itIs it a fluke of nature

   
What do you think?
« Last Edit: 02/09/2016 12:23:01 by _system »


 

Offline AndroidNeox

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Is what a "fluke of nature"? Is this a question about physiology? Biochemistry? Mammalian evolution?
 

Offline evan_au

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Milk is produced by the mammary glands.
The mammary glands take raw ingredients from the bloodstream and turn it into milk. Milk is close to the bloodstream, but it doesn't taste of blood.

The intestine breaks down food and turns it into small-molecule nutrients which make it across the intestinal wall and into the bloodstream. These small molecules don't smell much like the intestines.

The liver takes these small molecules  in the bloodstream and detoxifies the blood.

In the case of a cow (or ruminants in general), there are several stages in the processing of grass, through several stomachs, each with a soup of microbes breaking it down into nutrients.

There are several barriers between the intestines and milk, with radical changes in chemical composition at each barrier. It's not surprising that milk doesn't smell like intestines. 
 

Offline alancalverd

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Man with all his achievements og being able to fly into space cannot produce fresh milk with these gradients ,

But woman can, as does every other female mammal, and IIRC human milk does not reek of fish and chips. That said, some small molecules such as allicin (garlic) and ethanol can be excreted through the mammary system, and some radionuclides and labelled pharmaceuticals can turn up in significant quantities in milk from any source.   

We can indeed manufacture artificial fats and proteins but the raw material, coal or oil, is generally more expensive than grass for which we have no other use, so cows, sheep, camels and goats turn out to be economic, if chemically inefficient, sources of dairy products. The fact that different mammalian milks have different flavors suggests that individual diet and physiology play a small part in milk production and I've no doubt that a baby seal or whale would find fresh cow's milk decidedly "grassy".
 

Offline evan_au

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Different glands in our bodies produce substances as diverse as sweat, insulin, prolactin, saliva, oxytocin, milk, bile, adrenalin, stomach acid, tears, earwax and pituitary hormone, all from the same basic mix of starting materials in the blood.

Beyond that is muscle cells, bone, brain, hair and toenails, all from the same blood supply.

A pretty amazing creation, huh?

We are just starting to understand the details of how it all works together, now we can read and manipulate DNA more easily.
 

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