How long it takes for a calf to be full grown?
A calf is in the womb for around 285 days (though the exact time
frame depends on the breed of the calf and the cow), and is raised
on the cow for 6 to 10 months until weaning. After weaning a calf
is no longer referred to as a calf anymore. However, it is still
undergoing growth until it reaches 3 to 4 years of age, which it
becomes a cow (or heiferette if it still hasn't given birth to a
calf yet) if it is female, or a bull if it's an intact male. Males
that are castrated are still known as steers even after they reach
maturity.