From Stardew Valley Wiki
Animals serve as a source of money and resources on your farm. They can typically be obtained only after a building is constructed on the farm that is suitable to house them (a coop for chickens, for example) and with the exception of the horse and the pet, must either be purchased from Marnie’s Ranch or hatched from an incubator. In either case, these animals arrive as babies and must grow into adults before they begin producing animal products.
Animals that live in coops (chickens, ducks, rabbits and dinosaurs) have a chance each morning of producing products (usually eggs) that can be gathered by hand. Using the Milk Pail. cows can usually be milked daily, and goats can usually be milked once every two days. Sheep can be sheared with the Shears when their wool grows in, and pigs can be let outside to dig up truffles.
Buildings can be purchased from the Carpenter’s Shop. and will be completed within a few days. The only way to have a building moved to a different location is to demolish it. To demolish a building that houses animals inside, they must first be relocated. This ensures that animals aren’t lost in the process. Having any of these buildings demolished will not give you the resources back.
Barns, coops and slime hutches house animals, silos store hay, and the stable unlocks the horse.
Animals that live in barns and coops have a friendship rating that can be seen by right-clicking the animal after petting. The rating is out of 5 hearts and is shown in half-heart increments, and determines how likely that animal is to produce higher-quality products if that animal is capable of producing them in the first place. Friendship can be raised by daily petting (right-clicking the animal) and feeding.
Like friendship, an animal’s current mood can be checked by right-clicking after petting the animal.
Animals do not die if not fed, but will become upset and cease production of animal products until feeding resumes.
Animals that live in barns and coops can eat either fresh grass (if allowed outside) or hay (if kept inside, or unable to find grass). These animals will have their mood changed to “very happy today!” upon eating fresh grass. Slimes only need to have their troughs filled with water from the watering can, and horses and pets do not need to eat.
Grass & Hay
Opening the gates of a coop or barn will allow animals to come outside (when the weather is not rainy, snowy, or stormy) and eat grass. The animals will return to their buildings in the evening to sleep. Closing the gates again in the evening is recommended in the case of goats, as their mood becomes “sad” if the gates are left open overnight.
If they remain inside or do not find grass to eat, they will instead eat hay.
Once a silo has been constructed on the farm, using a scythe on grass will place hay inside the silo. Each silo holds 240 pieces of hay . Hay can then be gathered from hoppers inside barns and coops and placed in the feeding bins nearby. Building a silo before building animal buildings can make care much easier, though hay can be purchased from Marnie’s Ranch even if the silo has not been built.
In the winter, snow covers the grass completely, making grazing impossible. As such, it may be advisable to use the scythe to cut some or all of the grass into hay before the end of the fall season to ensure enough reserve hay to feed your animals through the winter.
These animals cannot be purchased until a coop is built on your farm, and must occupy a spot in a coop. They will leave their products inside the coop each morning.
Chickens have a chance to produce eggs every morning. Happier chickens may produce larger, more valuable eggs.
Pigs will automatically find Truffles after being let outdoors. Truffles can be used in the Oil Maker to make Truffle Oil.
Grazing will be affected by Foraging skill, allowing to always gather gold quality Truffles with a chance of double harvest.
During Winter, pigs will not produce Truffle, since the field is covered in snow and they won’t go out of the barn.
The horse can be ridden to make traveling faster. If you leave it somewhere, it will find the way home by itself. It is obtained by purchasing the Stable from the Carpenter’s Shop. The horse comes with the stable.
Slimes are unique in that they are not docile and harmless like other animals. They are similar in appearance and behavior to Slimes found elsewhere in the game, and will attack and damage the player if able to. They are obtained by placing a Slime Egg in a Slime Incubator. either a player-crafted one or the built-in one that comes with the Slime Hutch.
Slimes produce Slime Ball. and do so only when both male and female Slimes (those with and without antennae) are present in the same location, and when given access to water via the troughs in the Slime Hutch. The Slime Ball can be right-clicked to release multiple Slime items. These piles of slime have a chance of appearing daily, much like the products of coop animals.
Male and female slimes will also occasionally breed with each other.
Slime Eggs can be obtained as rare drops from Slimes or by compressing 100 Slime items in a Slime Egg-Press. They come in various colors and will produce slimes of the same color as the egg. Slimes of any color can breed with slimes of any other color.
Slimes incubated or bred in this way can be fought and killed just like any other slimes, and will drop items. A slime hutch can become a very dangerous place after even a few eggs have hatched, and it is advised that players take caution. It is recommended that the player obtain the Slime Charmer Ring before attempting large-scale slime farming.
It is also important to note that once the hutch has more than 5 Slimes, there is a 3.5% chance per night per slime to escape and disappear.
The player is allowed to adopt either a cat or a dog . the animal they adopt is dependent on which they choose as their favorite in the character creation menu.
The animal chosen will appear at the beginning of the first Spring 12. (Since the last patch on February 28, 2016 you might get your pet earlier than day 12.)
You will be able to choose any name you want for your pet the moment you adopt them.
You can click on your pet once a day to pet them and they will show you their love .
There’s a bowl on some tiles on the top left side of your house, you can fill it with water for them. The bowl is purely cosmetic.
Certain animals in Stardew Valley cannot be interacted with, and certain ones of these only appear in certain seasons.
Butterflies are abundant, and come in many colors, though they can only be seen in summer. To see butterflies, walk around, or shake trees.
Owls as they can only be seen in data.
Owls are somewhat uncommon, and can only be seen at night (7:00pm-2:00am). They have been seen in the summer and fall.