Cows don’t have to be milked at all! They make milk for the same reason that human women make milk: only when they are pregnant, in readiness for feeding their newborn. If cows are not impregnated, they do not produce milk.
Naturally, cows would choose their mate, would give birth infrequently, and spend time suckling their young, forming a bond and protecting them. But the milk industry is ruthless and to keep the milk flowing, cows are impregnated year after year, no matter the toll it takes on their bodies. In fact, most dairy cows are exhausted, lame and spent by the time they are six, and are sent off to slaughter where their bodies are turned into low-grade meat products. Without the strain of constant impregnation, birth and separation from their young, cows could live to 20 years or more.
Of course, milk is not the only outcome of pregnancy. Calves are born, too. Female calves may be reared and used as milking machines themselves, and will endure the repeated cycle of forced impregnation, birth and loss of their young to replace their own mum when she is deemed useless and is slaughtered. If the calf is male, he may end up on a veal farm; he may be allowed to grow and then slaughtered for low-grade meat; or he may be shot at birth if money cannot be made from him in another way.
Whatever their fate, the calves are taken from their mothers within days of birth. Both mother and child grieve for one another. It is well known that mothers bellow for days, calling and calling for their lost young. There are just a few former dairy cows who have been rescued while pregnant and have finally been allowed to keep their baby. The sanctuaries that care for them report that the bond between mother and child is incredibly powerful, but most cows will never experience it. And before they are over the loss, they are impregnated again, and the cycle continues.