In Real Life, cows are not able to be milked year round. Like most mammals, cows make milk only for their offspring and thus only lactate during pregnancy and directly after pregnancy, and even then, they only lactate during a warmer season. Cows need to constantly be pregnant (being impregnated once a year) and be in a warm temperature in order to make milk. Even then, cows will eventually stop giving milk with age, which leads to the cows either being retired or sent to the slaughter.
In fiction, however, cows can be milked even when they haven't had any calves. Cows can be milked even when the weather is unsuitable for lactating. Cows in fiction lactate no matter what. The only time they'll stop is when sick, old, or starving. This is because cows are mainly known for producing milk. In video games where cows and their milk are a resource, this spares the logistics involving animal husbandry and managing the calves. Sometimes, udders are a Weapon of Choice for the cow, with the milk being Edible Ammunition.
This trope also applies to other animals used for milk, such as goats and buffalo.
Sub-trope of Artistic License Biology. Milking a cow might be part of Everything's Better with Cows. May overlap with Animal Gender-Bender if the cow is male. See also Cow Tipping for another trope about fictional cows being portrayed inaccurately, and The Simple Life Is Simple for other agricultural misconceptions. Has nothing to do with Milking the Giant Cow.
- Zigzagged in the Akazukin Chacha TV series. When the characters need to find milk for a giant baby, they observe that they need to find a cow that's recently had a calf. However, there's one all-too-conveniently available.
- Daily Life with Monster Girl: Minotaurs lactate constantly, so they need to be milked. Of course, they have human-like breasts rather than udders, since it's an ecchi comic.
- In Diary of a Wimpy Kid: Cabin Fever, Greg mentions that his dad wouldn't let him take home a goat that he won from the state fair. Greg thinks that the goat would be able to give him milk whenever he wants, despite the fact that the goat wouldn't have any kids if it is the only goat that he would have.
- Averted in the Little House on the Prairie books, where the family's cow stops giving milk when the hard winter comes.
- Seemingly played straight for most of Green Acres, but subverted in at least two episodes. In season 1's "Lisa Has a Calf", the Douglas' cow, Eleanor, has a calf, justifying the fact that she had been able to be milked thus far in the series. In season 4's "A Husband for Eleanor" she stops giving milk, and the plot revolves around finding a bull to breed her with.
- The Last Man on Earth: The group is overjoyed in season one to discover that a cow managed to survive the virus as it means they get to have fresh milk. Whilst the cow does end up getting pregnant, they still milk it even when its not. Likewise after it dies, they just go to milking its calf.
- Cows in the Farming Simulator series always produce milk, thanks to the fact that Eternal Equinox is also in play in vanilla. This is averted in the Seasons mods for these games by Realismus Modding, cows will only produce milk after they have given birth though they are artificially inseminated which requires no input from the player. This can be further averted with a mod for the GlobalCompany script extension in 19 that only milks them every half-day.
- In Farmville you can milk cows, and you can breed them, but you don't need to breed them in order to be able to milk them.
- In The Legend of Zelda: Ocarina of Time, you can make any cow instantly produce a surplus of milk by playing Epona's Song on the ocarina while standing next to it. If you have an empty bottle, it'll let you fill the bottle with milk in gratitude for playing such a nice song.
- Minecraft: Cows are a One-Gender Race, but they and their Planimal cousins the "Mooshrooms" can also be milked with a bucket anytime (though there is a cooldown of about five minutes). With a bowl the mooshrooms give mushroom stew.
- In Mother 3, there is a cow which you can milk if you interact with to receive the HP-restoring item, Fresh Milk. More Fresh Milk can be obtained in this way at any time so long as there is no other Fresh Milk in your inventory. There isn't a calf to be seen.
- In My Time at Portia, cows start producing milk once they reach adulthood. You don't even need to actually milk them: bottles of milk will just appear in their pen overnight as long as you keep them happy and fed.
- Miltank from Pokémon is a cow Pokemon whose signature move is Milk Drink. It's also the source of the Moomoo Milk item. Miltank don't need to be pregnant (which only occurs while she's at a breeder as with all Pokemon). It doesn't even seem that any Pokemon are truly mammalian, as they all reproduce through eggs and young Pokemon eat solids as soon as they're hatched.
- RimWorld has several animals that regularly produce milk once they grow into adults. There's no need to keep males around unless you plan on breeding or eating them.
- Stardew Valley has cows and goats who will give the farmer milk every day (though goats lactate every other day) if they're fed and cared for every day. Given the best care, and the farmer will be given Iridium quality Large Milk.
- Story of Seasons:
- In most titles, all adult cows can be milked year round. They only stop lactating when sick. As soon as a calf turns into an adult, she can be milked.
- Subverted in Harvest Moon: A Wonderful Life, which strives to be more realistic than the rest of the series.
- Cows only give milk for two seasons before they need to be bred again. The quality and quantity of the milk also slow down just before they stop giving milk. This justifies the existence of bulls, whose entire purpose in the game is to impregnate cows. If you don't have bulls, you have to pay to borrow bulls from other farms. Also, if you buy cows, don't expect them to lactate for you immediately, because you have to breed them first. According to Takakura, the reason why the cow you start the game with can lactate for free is because she just recently gave birth.
- In the original game, the goat can also only be milked for a period, but she can't be bred or sold. The only way to get rid of her was to let her die. Another Wonderful Life and A Wonderful Life: Special Edition fixed that by allowing her to be sold.
- Marge from Toonstruck is an anthropomorphic cow who laments her butter-making Churnatron being out of order due to a missing part. Once you find that part and it gets reattached, Marge will attach the machine's suction caps to her udders every few seconds to produce butter.
- Viva Piñata: Moozipans and Flapyaks are able to produce milk by simply feeding them a sunflower and then directing them to a milking shed. If they are wearing a bell, the sunflower isn't even required.
- In Hay Day, cows always take an hour to regenerate their milk after being fed, no pregnancy needed.
- The Adventures of Puss in Boots: Pajuna, the bartender, is an antropomorphic cow who serves her own milk. She doesn't have any calves, and there is no sign of her ever being pregnant over the entire course of the series.
- Cow and Chicken: Cow is able to milk herself, often squirting it at villains as Supercow. The thing is, she is supposed to be a child, and probably not even entering puberty yet.
- The Loud House: In the episode "Pasture Bedtime", one of the animals on Liam's farm is a goat. Despite being the only goat on his farm, and therefore not having any kids, she is still able to make milk. This comes in handy when Lincoln and his friends try to make Liam fall asleep with the milk.
- The Simpsons:
- The "Treehouse of Horror" special "The Isle of Hibbert" has Ned Flanders turned into a half-man-half-cow creature (he has his own torso but a cow's body, similar to a centaur) and is in pain from needing to be milked, even though he hasn't recently had calves.
- The Itchy & Scratchy Show episode "Butter Off Dead", Itchy shoves Scratchy into a cow's mouth, and after Scratchy is digested, Itchy is somehow able milk him out through the cow as butter. Not only does the cow not appear to be nursing, but cows don't milk out what they digest in real life.
- SpongeBob SquarePants: The Season 11 episode "Shopping List", has SpongeBob and Sandy milking a giant fangtooth fish (apparently the underwater equivalent of cows) who does not have any fries with her.