When does cows milk come out of a cow before delivery?

Answer 1

This depends on the cow, actually. Some cows may start lactation right after her calf is born, others (and this may refer to most) will start freshening (producing milk) a few days to even a few weeks prior to giving birth. One of the classic signs that a cow is about to give birth is that her udder and teats start to engorge themselves with milk.

Answer 2

Milk never comes out of a cow by itself, and never before delivery of the newborn calf. Milk is suckled by the calf after it is born, and only by the calf whenever it is hungry. However, if the cow is a dairy cow, milk comes out by either hand-milking or by a vacuum pump-driven machine that is hooked up to the teats.