In what way are cows harmed by the production of cows milk? It's obvious that meat comes from an animal that had to die, but you don't need to kill a cow to get her milk.
In the most ethical dairy farm I could imagine while still having real cows and real farmers, but maybe not real economics, the dairy cows are harmed by having to give milk much longer than their calves need. They're milked four times a day. One might expect that they'd need to be herded into the barn each of those times, so that they can be milked, but the herders are very gentle about it, and it only takes a few days for most cows to learn the routine after their calves have started feeding less. Frequently, the cows will herd up to the barn before the farmhands even go to start milking, and on an established farm, cows will frequently learn to huddle for milking from following the others.
While cows aren't as dumb as we make them out to be, they're also not the brightest of animals; they shouldn't train that quickly. They are herd animals, so learning from each other isn't that surprising, but when a new dairy farm is just starting out, and there's only one or two cows that have gotten to the point of producing milk the farmers can take, learning to leave the herd for this is a huge deal. Someone who is more empathic might realize that even being milked four times a day, they experience a significant amount of pain at milking time.
This utopian farm also has a couple of serious problems: milking the cows so often is a man-power intensive activity for the amount of milk collected each time, and even with such intensive milking, a dairy cow only gives milk for so long after they give birth. The intensive milking extends it by a significant margin, but it doesn't make the milk keep flowing for the rest of the cow's productive career.
Farms like this probably existed back in the day, but mostly as a farm that raised cows for slaughter, and the dairy was a secondary product, rather than the focus of the farm.
The next step less humane keeps the calves from their mothers. Instead, they're fed from a bottle. The mothers go on the pumping machines immediately after they start producing milk. The calves get less milk, which means more milk to sell. The calves are slightly malnourished until they're old enough to live on solid foods.
Economically speaking, this isn't much better than the ideal. But it's the picture of dairy farming that I was raised to believe when I was a child. At the time, I was living on a farm, and the focus was supposedly more on teaching what farming life was like. But even with that focus, there were details of the neighbor's farming practices that my parents didn't tell me about.
The next step to making dairy farming profitable is to ship the male calves away to other farms as soon as possible. Many of these calves become veal, so that they don't even have to make it to handling solid foods. Slightly more milk, and the excessive number of male calves is dealt with. At this point, you're killing baby bulls to get the milk they'd have drank. As I understand it, this is the level of ethical of the first pure dairy farms. It's possible that the first farms just raised the male calves to sell to other farms to raise for slaughter as adults, but there was still implicit slaughter as part of this arrangement. The neighbors didn't talk a lot about doing this. When I was a child, I didn't even know what veal was, not even in the item on the menu sense. But I learned it had always been a thing on one of my last visits.
But we still haven't addressed the fact that the cows are only giving milk for a few years at a time until they get pregnant again. So now the dairy farmers institutionalize either artificial insemination to keep their cows producing milk all of the time, or they use things like rape racks to hold the cows still so that the farm bull will impregnate them when nature hasn't taken its course quickly enough. There's now an overproduction of both boy and girl calves, so more veal.
This is the reality of the dairy farm "next door" I had been raised to believe was ethical. They used a precursor of a rape rack, but it was still much the same thing; the cow just got a slight amount of ability to evade the bull, rather than no amount. The farmer described it as 'just putting the two "love birds" in a pen and letting nature take its course'. This explanation was given one time we were visiting and this happened to be going on. It was a loud process, as the cow banged into the wooden walls around her repeatedly in her efforts to escape the bull. But the natural process doesn't work 100% of the time, so they still resorted to artificial insemination if that didn't work for some reason.
Milking machines reduce the amount of manpower needed to milk the cows. These machines have no ability to sense when they're hurting the cow, so at least the end of each milking experience will be painful, unlike someone milking by hand who could observe the cow to see when it's starting to feel unpleasant and be gentler for the final few squeezes. There's probably more inhumanity with the milking machines than I'm aware of. When our neighbors had been hand-milking while we were over for a visit, the cows still waiting for milking would be making noises that sounded something between a moo and a bellow, which the farmers called "lolling" (I'm not sure about the spelling, I never saw it written.) With the milking machines, at the end of a milking, the cows made a very urgent-sounding bellow which sounded much more distressed than even calf separation.
Under normal circumstances, a cow's udder can hold more than 6 hours of milk; it's just really uncomfortable for the cow. But you can get more milk per man hour if you don't milk the cows quite so often. It requires more cow rape to make up for the reduction in how long the cow gives milk, but managing that as often as you need to keep the cow producing all the time takes up a lot less time than all that milking. I only know of this from our neighbors discussing the next step to becoming more profitable and not wanting to go there.
But modern farms have found a way to do even better than this: milking equipment is just a one time cost, so keep the cows in the barn, in a stall where they can't move pretty much all the time, and you can almost eliminate the cost of your farm hands' milking labors. At this point, milking the cows is just flipping a switch to start, and then flipping it back when too many cows are complaining.
I would like to think that we haven't come up with more inhumane ways to collect milk than this. Unfortunately, I don't have that luxury. It's my understanding that the one less humane way I am aware of to farm dairy has been made illegal, so I don't need to go into it. We've probably come up with something else to get closer to that precipice again.
There apparently have been a few farms that at least came close to the ideal I listed above. They managed to do this by charging a lot more for the milk they produced and/or making their real money by other means, such as donations.
Most of my knowledge of this is dated; my family moved away from the farm around 1979, and I think the last time I visited those neighbors was 1993 or so. At that point, they had opted to retire the dairy farm, as it was too much work for too little money, and they weren't willing to take the steps to make the operation profitable. It's been my impression that the general trend in the industry was to move increasingly inhumane.
If you only look at the body count : to have milk, there must be a baby veal. That animal won't get the food it needs (since we are taking the milk) and is slaughtered if it's a bull (a baby cow will become a dairy cow). The veal industry benefits greatly from the dairy industry. So even if your only requirement is no animal death, dairy products aren't obtained without victims. Also, the lifespan of a dairy cow is 4 to 6 years. The lifespan of a cow is 18 to 22 years. So even if they aren't slaughtered for their milk, being milked and used like that reduces their lifespan drastically. And those cows will then in turn be sold as ground beef and hamburgers.
But also, killing is not the only way to inflict harm :
- A veal is taken away from it's mother 24 hours after being born. Cows are very attached to their young, being separated from them so soon provokes great distress and emotional harm.
- They are isolated inside, barely being able to move.
- They're milked while being pregnant. This hyper productivity and the fact that they're confined creates lots of illnesses and aches.
These problems occur in big dairy farms, but also in smaller, more "ethical" farms. In an ethical farm, they might let the cow go outside, but they still separate the veal from it's mother hours after the birth. Or they get the cow pregnant back to back, milking it while it's pregnant, to get the most milk out of it but tiring it out in the process, and killing it at only six years old. Having both a truly ethical and profitable dairy farm is a miracle. In the end, if a farmer wants to sell milk and earn money, it has to abuse the cows in some way.
Humans are the only creatures who drink milk even after the very first years of their life, and they don’t use their own milk to drink; in the dairy industry they force cows to become pregnant all the time so they can get the milk they want, because animals can only lactate after pregnancy.
And if you think they let the cows get pregnant by having sex, you are totally wrong! They are artificially inseminated
And what happens when their babies are born? Simple! They are taken away so that they don’t drink the milk which we think belongs to us.
Cows are intelligent animals and they can feel the pain of alien creatures taking their children away. I watched videos of them crying for days about this.
After all these misery they will be killed for their meat because they won’t be able to stand on their own feet because of the pressures on their bodies of constant pregnancy and excessive lactation.
If you're asking about farmers who treat their cows nicely, like you mentioned in your question, okay, they exist, but people who are not able to observe the conditions the cows whose milk they drink are living in should avoid dairy if they want to avoid harming cows.
This YouTube video by Eric Janus contains everything I've said with video evidence.