I suppose it depends on how far you stretch out the idea of “healthy” as an option. Healthy for whom? For what? Healthy for people or healthy for animals or healthy for the planet?If cows are raised for milk, they have to be produce a calf to get that milk turned on. That calf is then either another dairy cow or a beef animal. Either way, it has to be fed on something, as do its parents. When I was a child, the farmer kept his cows out in the fields eating grass for a good amount of time. They gave birth in the fields and kept their calves at their feet. Now, in many places, cows live indoors and eat artificially produced food. They are nothing more than meat and milk factories.Each person must decide for themselves whether what they eat can be justified as “healthy”, for whatever that is, be it themselves, the animals in question or the planet.
It's the beef and dairy in the US and Brazil etc that is carried out in confined 'lots' or inside buildings as you describe.I deliberately didn’t specify which countries. I was only interested in showing the effect on the planet. I don’t know how the cattle raising industries of the USA and Brazil compare in size to the British cattle raising industry, but I imagine it’s “lots”.
My grandparents and uncle ran a dairy farm, the cows spend the winter in barns fed on silage and cow nuts (which uses arable products including imported soya these days).