Did you just blow in from stupid town or something?
They didn't say "before pregnancy" they said they have to "continuously" be pregnant. Which is true, the mammal body only produces milk for an upcoming child. Which dairy farmers strip the child away from the mother right after birth, to then take that nutrients from the mother (meant for the baby) for human gullets. They then need to repeat this process until the mother is no longer of use to them. It's fucking rape and constant exploitation for these animals. I fail to see what your gotcha was here.
Please continue though with the explicit details of your animal exploitation experience, it isn't the badge of honor you think it is.
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Give it a couple months, they'll get there.