After a mouthful of curdled milk, I came to ask myself: How come milk does not spoil while it is in the cow? The winning theory amoung friends and family is that the cow is a fairly sealed and sterile environment, however, I dont believe this.
Thanks for any imput.
Spoiled cows don’t have to give milk. 
The real answer is that the milk isn’t in the cow long enough to sour.
Peace,
mangeorge
Haven’t researched all about it, but they’re right about the sealed and sterile part. Same reason milk doesn’t spoil in any animal that produces it. If the inside of any animal were as open to the elements as your carton of milk in the fridge and had no immune system, they’d be dead in a few days.
I don’t think milk is sterile.
From m-w;
Peace,
mangeorge
I think this is a durn fine question (translation: OOH, OOH, I KNOW THE ANSWER!)
Unfortunately, mmmiiikkkeee beat me to it.
Nevertheless, since I so enjoy the sound of my own typing, I’ll elaborate on his response.
The inside of the udder is normally sterile. There are at least four reasons for this:
[ol]
[li] The milk ducts are kept tightly closed, except while milk is flowing.[/li][li] Milk, once produced, is only stored in the udder for a short time.[/li][li] Milk only flows outward.[/li][li] The cow’s immune system (mainly IgA antibodies) mops up whatever bacteria that happen to make it in.[/li][/ol]
Interfere with any of the above, and Bossy will likely develop mastitis. The same general principles govern the infectibility of any sterile body site with a natural or iatrogenic (made by your friendly MD) opening.
**
Milk is pastuerized to kill disease causing and milk spoiling bacteria. Most of these organisms are picked up once the milk exits the cow’s udder (i.e. they are skin flora). One notable exception (IIRC) is Mycobacterim bovis. This organism, related to Mycobacterium tuberculosis, causes scrofula[sup]*[/sup] in humans. The organism sets up an indolent infection within the cow’s breast tissue. Organisms flow out of Bossy along with her milk.
[sup]*[/sup]SYLLABICATION: scrof·u·la
PRONUNCIATION: skrfy-l
NOUN: A form of tuberculosis affecting the lymph nodes, especially of the neck, that is most common in children and is usually spread by unpasteurized milk from infected cows. Also called struma.
ETYMOLOGY: Middle English scrophula, from Late Latin scrfulae, swelling of the glands, diminutive of Latin scrfa, sow. See sker-1 in Appendix I.
Here is what I am thinking: the temperature in a cow is around 90 some degrees. How long does it take for whole milk to spoil if it were left in 90-something degree room? Not very long, I would suppose. So really, how long are you thinking the milk waits there?
It the milk were sterile (as it is within the cow’s breast tissue), it could sit for a very, very, long time at 90[sup]o[/sup]F without spoiling.
That’s If the milk were sterile, of course.
You beat me to this, but without the emphasis some people may have missed it. 