Well, I grew up on a cattle ranch so I’ll throw in my 2 bits.
If you see a single animal in the distance, you can say “who’s cow do you s’pose that is?”.
If you are near enough to distinguish its sex and it’s really a bull or steer you will be ridiculed by your dad and all other male adults.
It seems like among cattlemen “cow” is acceptable for a single animal if you don’t know the sex.
It’s even more common to refer to them by size, as newborns, calves, yearlings, or feeders when they’re young.
One last thought, when my relatives from town came out to visit us they seemed to have a driving need to “moo” at the cows. I often wondered what the cows thought of that.