A Cow is an animal that can be purchased at Marnie's Ranch for data-sort-value="1500">1,500g, after owning a Barn. Cows come in two varieties: White and Brown. When purchasing a cow, the game decides randomly whether you will get a white or brown cow (50/50 chance).
Care
When you right click on your cows it will bring up a window showing their age, number of hearts, and a brief statement on how they're feeling. You can also move them to another barn, sell them, and select/deselect the "allow pregnancy" option.
Produce
Cows mature after 5 days, at which point they will produce Milk every morning, unless they are grumpy, in which case milking them will result in the dialogue "[Cow Name] has no milk right now". When friendship is high enough, they will produce Large Milk. Milk can be collected using a Milk Pail. Milking a cow increases friendship by 5 points.