The natural lifespan of a cow is up to 20 years, yet few...

The natural lifespan of a cow is up to 20 years, yet few commercial dairy cows live beyond the age of seven years, and many younger animals go to slaughter.

Selective breeding and, more recently, genetic manipulation, has resulted in the selection and production of cows who produce enormous amounts of milk.

The modern dairy cow can produce about 35-50 litres of milk per day—about ten times more milk than her calf would need.

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