In order to have chickens on your farm, Gannon must build you a chicken coop. The most basic chicken coop can be built with 150 pieces of lumber and 5,000G.
Mirabelle will be kind enough to give the player a free baby chick after the coop is built. She also has adult chickens for sale at her shop for 1,500 each, making them one of the most inexpensive animals. Baby chicks can be hatched from eggs placed in the incubator. The egg will hatch in 3 days, and the chick will grow into an adult in 8 days if you feed them every single day. If you miss a day of feeding, it will add the day that you missed to it's growth rate. The number of friendship points (hearts) the new Chick will have is determined by the Quality rank of the Egg you use, times 5, and divided by 2.
Adult chickens will lay an egg every morning. Eggs sell for low profit in comparison to milk or wool, but you don't need to wait a few days for chickens to lay their eggs.
Chickens will eat Chicken Feed, which can be purchased from Mirabelle's shop for 10G a bag. Each individual chicken will need their own feed box. If chickens are left outside, they will eat worms out of the ground and you don't have to feed them. Once you increase a chicken's heart points to 8 or higher, you will win the Chicken Festival if you've entered. Your chicken will then start to lay s-rank eggs, and you will unlock the ability to purchase Silkie Hens.