They require one Poultry Feed or Livestock Feed every day, or they can eat weeds and Fodder. Not feeding the animals can cause them to die.
They can be bought at the Ranch. Some animals in the Poultry House can be hatched from eggs in the Hatchery. Animals in the barn can give birth if both animals' fondness is full and there is space in the barn.
Animals produce better quality products when increasing their fondness (relationship). They also sell for more with higher fondness, make sure to sell them at max fondness.
Petting them by clicking on them will increase the fondness. You can only pet them once per day.
It can also be increased by gifting them Love Dough, when they are not full/fed, which can be crafted in the Bait Workshop.