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Do Cows Have To Be Pregnant To Produce Milk?

Do Cows Have To Be Pregnant To Produce Milk

Cows only produce milk while they are pregnant, or just after they have had a calf.

To keep dairy cows as productive as possible, they are kept perpetually pregnant, usually giving birth approximately once per year. This minimizes the time between the end of the lactation period (which lasts for around 10 months after calving) and the next birth to just 2 months of the year.

In this article, we’ll look more at when exactly cows make milk, and how farmers keep them pregnant and productive. We’ll also explore some interesting questions around how we actually get the milk without the calves drinking it all!

Do Cows Only Produce Milk When Pregnant?

Dairy cows only start producing milk once they are pregnant, although they keep producing milk for around 10 months after giving birth. It’s this period after giving birth (known as the lactation period) when farmers harvest the milk from the cow.

As it happens, most dairy cows are impregnated again around 60 days after giving birth so that once the lactation period comes to an end, there is another calf almost ready to be born so the cycle can start again with as little downtime as possible, meaning most dairy cows are actually perpetually pregnant while they are producing milk.

The period between one lactation ending and the next beginning is called the dry period and is usually around 60 days long. This is because farmers wait 60 days after calving to reimpregnate the cattle.

The reason for the 60-day wait is because reimpregnating a cow sooner than 60 days after giving birth leads to a whole host of problems, including lower milk production and an increased risk of disease.

Can Cows Produce Milk Without a Calf?

Cows must be pregnant or must have recently given birth for them to produce milk. In that sense, cows must have given birth to a calf to create milk, however, the calf does not need to be physically present for the mother to produce milk. In fact, calves are usually removed so that farmers can harvest the milk for human consumption instead.

In most dairy farms, the calf is physically removed from the mother after around 24 hours. Male dairy calves are typically sent to be humanely slaughtered, or sent to be used for veal. Female dairy calves are often kept on the farm and raised to be added to the dairy herd.

Read More: Do Cows Understand Slaughter?

Once the calf is removed, the mother continues to produce milk for around 10 months.

Don’t The Calves Need The Milk we Take?

Like all mammals, cows produce milk for their own young. Although there may be a moral argument against whether or not you should drink milk that wasn’t made for you, the truth is that cow calves grow up perfectly healthy on a diet of synthetic milk, and modern cattle have been selectively bred to produce more milk than a calf could ever drink anyway.

For a few days after the calf is born, the mother cow produces special milk called colostrum, which contains crucial antibodies that help the calf fight off infections and disease. Farmers let the calves drink the colostrum because it’s important for their health, and it’s not suitable for the human food chain anyway.

Read More: Why Do Humans Drink Cows’ Milk?

Some dairy farmers choose to keep a certain percentage of the milk yield to one side for the calves, whereas some feed the calves solely on synthetic milk.

Modern dairy cows (Friesian-Holsteins) produce up to 28 liters (over 6 gallons) of milk every day. This is considerably more than the requirements of a single calf, which only needs around 10% of its weight in milk each day. (For a 90lb calf, this means that a productive dairy cow can produce up to 7 times as much milk as the calf requires)

How Do Farmers Keep Dairy Cows Pregnant?

Farmers keep dairy cows pregnant by strictly controlling their reproductive cycle to maximize the overall time spent lactating. Farmers impregnate cows either by artificial insemination or naturally using a bull.

Farmers have two methods of keeping dairy cows pregnant, each with its own pros and cons.

The first and most popular method is artificial insemination, where the cows are bred with a medical device called a straw.

The pros of artificial insemination include the cost and space savings of not having to keep a bull, a higher rate of successful breeding, and the ability to keep an entire dairy herd on the same reproductive timeline. Although this method has lots of positives, there is still some debate over the ethical implications of artificial insemination.

The other method available to farmers is natural breeding, where a bull is used and allowed to breed through the natural process.

This method also has its pros and cons. Keeping a bull is expensive. According to NADIS (the UK’s National Agricultural Disease Information Service) the cost just to keep a bull for a year can exceed $2000. The major advantage of using natural breeding is that the farmer doesn’t have to monitor the cows to check when they are in heat.

Related Article: When To Start Milking A Cow After Calving?


To sum up, cows only produce milk after they have had a calf, so they are kept in a perpetual cycle of pregnancy and lactation to ensure maximum milk production over the course of their lives.

A dairy cow produces milk for around 10 months after she has given birth. This is called the lactation period. Roughly 60 days after calving, cows are impregnated again so that there is only a minimal amount of time between the end of one lactation period and the beginning of the next one.

Cow calves are usually removed from their mothers soon after calving since it would be unsanitary to allow the calves to suckle milk destined for the human food chain.

Instead, calves are usually fed on a mixture of synthetic milk, milk replacer, and waste milk until they are old enough to eat solid food.

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