> modern breeding can select for heifers with ~90% confidence

May you expend on this? I know we kinda have selection techniques for eggs to crush them before hatch but I guess that’s not what’s happening with milk caws as the diary is the main target and the cow need to give birth to start lactation. Or perhaps it’s the impregnating technique or some hormone therapy that tricks the odds?

> in this day of age of high-priced beef, even if you get the occasional bull you're not exactly complaining either.

I depends on the breed: in this days of high volume diary and meat consumption, most of what people eat comes from specialised breeds that hare very good at producing milk OR muscle. The non-desired sexed are not so valuable. Switzerland (and others countries I can’t remembers) recently passed a calves handling low to require farmers caring them for a minimum days in response to industrial sloped into unethical territories.

That documentary shows another practice in India : some invaluable calve are just roped to a fence and forget until dehydration. https://christspiracy.com