(NY) The New York Times – Three years ago, a technological breakthrough gave dairy farmers the chance to bend a basic rule of nature: no longer would their cows have to give birth to equal numbers of female and male offspring. Instead, using a high-technology method to sort the sperm of dairy bulls, they could produce mostly female calves to be raised into profitable milk producers.

Now the first cows bred with that technology, tens of thousands of them, are entering milking herds across the country — and the timing could hardly be worse. More