We don’t help only cows, we milk a whole lot of mammals. Admittedly many mammals aren’t all that into being milked, and many (if not most) of the carnivorous animals won’t let you hang around long enough to see if they do, or do not, consent, but it’s not solely because we like milk, nor is it solely parasitic (and certainly not solely slavery). Humans have milked orangutans to feed baby orangutans, milked giraffes to feed other giraffes, and milked elephants because, rather like cows, they can get right cranky (and downright dangerous) when there’s insufficient young to remove the excess. For that matter we help our own species, at times, express milk that
needs to be expressed — admittedly in that case usually (one hopes) with explicit verbal consent. Nature does not make precisely one teat per toddler, nor does nature produce precisely one portion per progeny. I’ll admit we’ve
primarily treated cattle like, well, cattle, but you give me a cow and a bull and sufficient forage and, assuming they like each other and I keep the predators at bay, I’ll soon have a herd and more milk than they know what to do with… if she’s had fewer than four calves (likely) and especially if she’s only had one, then on a roughly daily basis she’ll be bursting at the seams and pushing up against all sorts of things for relief.
I get where you’re coming from, but I’ve seen with my own eyes cows essentially orgasm when someone finally helps get the first really cheezy, frothy, kinda curdled bits out of a neglected nipple. Now I for one wouldn’t go saying I like that milk, I wouldn’t even say I’d come close to consider drinking it… but I’ve seen enough looks of ecstatic delight on enough mammals (of a great many species) to know that it can be a relief to express the unexpressed, and the species doing the expression isn’t of that much issue at all times.
Ever seen the eyes of a shark roll back into its head when you find the bit of obviously dead skin it hasn’t been able to rub off and hasn’t been able to get a wrasse hole near and you give it a back scritch where it by evolutionary design can never reach? I have. Am I imagining that ecstasy? I mean probably… but said shark kept coming back to me for like half an hour. Maybe it was brain damaged, but maybe my choice to do what it didn’t verbally consent to was nevertheless what it was hoping something would do, to whatever degree it can hope. Or maybe I did a shark a dirty and I should feel ashamed… or, for that matter, maybe a shark did me a dirty and both of us should feel ashamed… honestly, not sure now, hence I’ll resolve the dissonance by continuing to assume I just helped out a creature that looked like it really regretted not having evolved fingernails and opposable thumbs.
What I sure as hell didn’t do was enslave that dogfish, any more than I’ve personally enslaved any animal.