1. Cows, like humans, only produce milk after giving birth

2. These cows, in order to get pregnant in the first place, are artificially inseminated (and it isn't a very nice process)

3. What do you think happens to the offspring if it's male and thus uneconomical to keep?

The fact that these statements (which are incredibly obvious if you have an eighth grade education or higher) have to be spelled out is a testament to the power of the milk lobby that people think there are some bucolic scenes where farmkids go to milk Bessie each morning, who produces day in and day out without fuss.