Hi Youra, that's awful...
But to answer the age thing, it's not easy to tell age, but you could sometimes see a hen with spurs, which would indicate that she's a few years old. And as birds age the scales on the legs tend to lift and look rougher, so that can be another way of telling whether a bird is old or under a year. Also lack of laying tends to go with age as well (though some birds keep laying through old age, and other breeds don't lay well even from the beginning).
In short, there's no way to definitively tell a chook's age, but you could probably be fairly certain whether a bird is 7 months old or over a couple of years.
I'm sorry you lost your new pet.
