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Do cows produce more milk than it is required for their calves? It seems like cows are able to provide milk all the time (all year around). Is it so? Or do they, like other mammals, produce milk only in ammounts requeired by their offspring?

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4 Answers 4

up vote 9 down vote accepted

Dairy cows are bred, or selected to give milk. So they do produce excessively. The normal bovine wild type, like other mammals, not only produce less milk, but also will tend to stop lactating when the calf is not nursing.

I would be interested to know if dairy cows stop giving milk if they are not milked every day. I understand they can get very uncomfortable if they are not milked, but i don't know if they stop giving milk or if they are injured in some way.

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Can you please provide a reference for the fact that if you milk a wild cow (good luck with that) every day, after removing its calf, it will stop producing milk at some point? Alo, if they are selected to produce more milk they do not produce it excessively. If you select a plant to have bigger fruits, its fruits are bigger, sure, but they do not grow excessively, they just grow the right size for that particular plant, which happens to be bigger than other plants. –  nico Mar 13 '12 at 7:23
@nico "The calf is not nursing" I think he means after the calf is weaned. Also, 'excessive' is a relative term. A cow producing 4 1/2 gallons per day would be considered poor by the farmer, but is excessive in terms of her calf's needs. –  J. Musser Mar 15 '12 at 1:59
@jmusser: that is what I am saying. If you get a wild cow and continue to milk it after weaning its calf it will most certainly continue to produce milk. –  nico Mar 15 '12 at 6:30

The average domesticated dairy cow produces far more milk than would be required to feed their calf. All cows, wild and domesticated, will only lactate in the period between their calf's birth and weaning. Milk is calf-food, and when there's no calf, there's no evolutionary advantage in producing milk.

On dairy farms, cows are milked twice daily, from spring (when they give birth) until late autumn. This mechanical milking 'fools' the cow into continuing to lactate. When a cow has stopped lactating, they will only start again after giving birth. This means that you can't just start milking a cow and expect to get milk.

Generally farmers milk their cows from spring (birth) until late autumn. The reason for stopping in autumn is simply because the grass grows much slower in winter, so there isn't enough food to support lactating cows. However, it is entirely possible to milk longer than a year; I know of farmers who milk their cows continuously for two years. These farmers will have to purchase a lot of supplimental food (like hay or silage) during winter. The advantage of milking for longer than one season is that the cows do not have to give birth every spring, but instead only every second spring.

I believe (but can't guarantee) that in winter, most milk purchased in a shop comes from the opposite hemisphere. I do know that here in New Zealand, we export a lot of milk to northern-hemisphere countries.

If you were to suddenly stop milking a cow, they might get sick but generally they will survive. It's still something to avoid!

I do not have an 'official' source for these facts. However, I grew up on a dairy farm, so this was my life.

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Thank you very much. This answer seems most informative and real-life applicable. –  Maxim V. Pavlov Mar 14 '12 at 9:51
I was under the impression that certain breeds (holsteins for one) have been so over bred for the milk producing trait that there are periods where there milk production is so high, not being milked can actually cause the udder to tear allowing them to die from sepis. Note: that's anecdotal I don't have information confirming or denying it. –  Christian H Mar 28 '12 at 21:50

Just an advice, it is better for cows to be not excessively producing milk, because they use a lot of energy for producing milk and thus are unable to care for their offspring, lowering that breed of cows to have a lower chance of survival.

On top of that, When their pregnant, it lowers their chances of escaping from predators. Thank you.

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Yes, they produce milk excessively. Even more, they get ill if their milk is not removed by a human.

Actually, cow is a bio-machine, generator of milk, developed by human thousands of years ago, and not a natural animal.

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-1: please source your answer –  nico Mar 10 '12 at 18:20
Also, "cow is not a natural animal" does not mean anything. Present-day dairy cows are a domesticated species (probably from Bos primigenius), but still "natural" (i.e.: they are not artificially created in a laboratory). –  nico Mar 10 '12 at 18:22
They were artificially created from a natural animal. –  Anixx Mar 10 '12 at 18:50
No, domestication is a different thing. Mycoplasma laboratorium is an example of artificially created lifeform. –  nico Mar 10 '12 at 20:13

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