It just comes in random.
They are just on your farm at a random day and time.
it is there in your gift box
It's totally random. Anyone of you or your neighbors can get them at anytime. usually it's during the normal time you or they are on the game, but it can be anytime. Usually a sheep or a cow.
If you found an animal in your farm, a box will pop-up asking if you want to help the lost animal. You could not keep the animal you found in your farm. You could only put it up for adoption, and your friends could adopt the lost animal. If you want that kind of animal for yourself you have to adopt it from your friends' walls.
Lost animals occasionally wander onto farms while people are playing Farmville. When this occurs, the owner of the farm has the option of trying to find this animal a home by publishing the story to their profile. The pet can then be accepted by the farmers Facebook friends.
Ive noticed that usually if you keep your farm up long enough they will wander on...like even after you are done harvesting just keep it on your farm and you should get one.
You can get cows on Farmville when your Farmville friends gift them to you or by adopting them when they wander across a neighbors farm and that neighbor posts a notification about it allowing you to adopt the lost cow.
A screen pops up while you are playing. You do not have to share it with friends. You can share it or not help the lost animal.
you cant adopt lost animals that wonder onto your farm you will occasionally see your friends posts on your wall on facebook home page that has a picture of a animal and at the bottom it says "adopt this animal" click and the animal should appear in your gift box.again you can not adopt animals than wonder on to YOUR farm-Goldiiibut only one person can get it so you have to be first
Lost animals show up randomly - there is no telling when they will appear.
Search your friends' Farmville news feed and look for lost animals that they posted. Click on adopt and if that animal isn't adopted yet, then you will.
They randomly come to you at random points in time.