The chicken and the cow disappear every day, is that normal ?

Animals have a short life, some more than others. A chicken dies after laying 16 eggs. You can check on an animal with a single tap on it. That shows how long til it will produce egg, milk etc, how many are left, eg 12/16 for chicken it can lay 12 more times. The blue option speeds up and it will immediately produce, costs an expedite egg timer.