[skak]

Only female cows produce milk.

[thaumasiotes]

Where do you get "half" from that? Female cows are economically productive and males are not. The ratio is not even close to half-and-half. Go look at a herd of cows sometime.

[aflag]

All cows are female.

[ummonk]

In common parlance (rather than technical terminology), "cows" means "cattle".

[thaumasiotes]

Almost all cattle are female. aflag doesn't get less accurate if you interpret "cows" as the species term that it is.