If your talking the magnets, yes the dairy farms still do because the more expensive the cow the more likely she is to eat something that's not good for her.
It was funny when after a discussion about hardware and what they would eat it was mentioned that an object that wouldn't hurt them and would pass right on through they wouldn't eat.
We tossed few coins (penneys and a couple of dimes and nickles on top of some grist for the dairy cows,
every single coin was on the concrete in the morning which had been licked clean.
The invention of poly twine for me is a mixed bag at best. Sure it beats sisal for longevity but you get poly wrapped around the underside of your mower head it will take out a seal right now and in a pickup, it's a mess too. Why I prefer net on rounds. With net you don't get any stray pieces on the ground to get caught up in machinery and in reality, the per bale cost with net is less than poly, especially if you hold your wraps down to 2 or less. My bailer runs both net and twine and I keep the twine section loaded just in case I have a net issue but that is a rare occurence, plus netting a bale is about twice as fast as twining one, even with auto twine wrap.
This year I never twined one round. Everything was in net.
It was always some fun for me. Everyone was focused and had a job to do. There was an urgency to get it done but not a panic. A feeling of accomplishment when it was done. Tired and worn out at the end of the day but the end result was great.