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While we had vets put magnets down cows over the years, my parents were too frugal to let me have one! There are two primary ways steel gets into the feed supp

While we had vets put magnets down cows over the years, my parents were too frugal to let me have one! There are two primary ways steel gets into the feed supply. A silage chopper can pick it up and cut it into fine bits or a hay baler picks up a stray end of wire and running large bales into a tub grinder to more easily mix feed stocks into a total mixed ration will chop the stray wire (and other parts) into moderately short bits. Many feed wagons have strong magnets under the discharge chute and grinder/mixers (used to grind grain and supplements) have likewise strong magnets just before the material enters the hammer mill. Despite that some bits will slip by due to the volume of material passing over the magnets as it comes out of the feed wagon. We do have the vets administer magnets to the heifers we keep at around 9 months of age. One has to watch to be sure they don't work them back up and spit them out! A couple of years ago we had some that did that. Symptoms of hardware is usually a cow "off feed" meaning she is not coming to the bunk to eat with the rest but usually stands apart and in acute cases will become hunched back. A veterinarian can usually diagnose it with a stethoscope as I think the breathing becomes labored in more acute cases.

DaiPlusPlus 2y ago
> my parents were too frugal to let me have one! Your parents wouldn’t let you swallow neodymium magnets?
- 0xdeadbeefbabe 2y ago
  Frugality first safety second
- throw_a_grenade 2y ago
  Now that you have come of age, you can proceed to ingest the damn magnet. Free yourself from the chains (sic) of the patriarchate!
- 01HNNWZ0MV43FF 2y ago
  Honestly it looks fun
- saagarjha 2y ago
  It’s fine if you swallow one. If you swallow two or more then you should probably go to the ER immediately.
- plowjockey 2y ago
  I probably didn't state that all that well. If I had really wanted one I'm sure I would have been provided one. It's equally quite possible that since they had to be obtained from a veterinarian that it never occurred to me to ask for one. OTOH, I did destroy a couple of old radios to get the speaker magnets. If I could go back in time I'd grab those old radios before I'd have a chance to destroy them. Back then they were just that--old radios--with no value and certainly not worth fixing. Sigh...
gumby 2y ago
> Many feed wagons have strong magnets under the discharge chute.. Even though I understand it's 1/r^2 this summoned a vision of a cow magnetically stuck to the discharge tube at her neck, with the head pushed up and mooing unhappily.
- marcosdumay 2y ago
  I think the force is actually 1/r^4. The magnetic field is proportional to 1/r^3. But the linear force is not proportional to it. (Rotations are.)
  - planede 2y ago
    It's 1/r^4 for magnetic dipoles, where both have fixed a fixed dipole moment. So it's 1/r^4 between two permanent magnets. Where one object is a permanent magnet and the other is some unmagnetized ferromagnetic/paramagnetic piece metal, then the dipole moment of that piece of metal also depends on the distance. Assuming it's proportional to the magnetic field of the other dipole (~1/r^3) then the force is going to be ~1/r^7 for this pair of objects.
    - marcosdumay 2y ago
      Oh, that's right. But magnetization is famously path-dependent, so now I'm tending to believe the force will be closer to 1/r^7 when moving on the direction of the magnet, but 1/r^4 when moving away. And not exactly any of those functions.
      - planede 2y ago
        Do you mean that the ferromagnetic material gets magnetized and retains some magnetization while moving away?
        marcosdumay 2y ago
        Yes.
SubiculumCode 2y ago
Got one once. Nice strong magnet with an odd shape....you can just imagine it going down the gullet.
peterleiser 2y ago
That's too bad. My parents were farmers and my dad brought some home one day, even though we no longer had cattle when we lived on our ranch. He thought I'd like to play with them, and he was right! Even my friends who weren't from farm families thought they were cool. I'm going to order some for my kids. These were the classic ones in the 1980's: https://en.m.wikipedia.org/wiki/Hardware_disease#/media/File%3ACowMagnet.jpg https://en.m.wikipedia.org/wiki/Hardware_disease#/media/File...
- dehrmann 2y ago
  My grandparents had a dairy, and growing up, I remember these on one of their filing cabinets. When I saw "cow magnets," I knew exactly what to expect.
wyclif 2y ago
Alnico magnets are the same type of magnets used in vintage electric guitar pickups.

DaiPlusPlus 2y ago

> my parents were too frugal to let me have one! Your parents wouldn’t let you swallow neodymium magnets?

0xdeadbeefbabe 2y ago
Frugality first safety second
throw_a_grenade 2y ago
Now that you have come of age, you can proceed to ingest the damn magnet. Free yourself from the chains (sic) of the patriarchate!
01HNNWZ0MV43FF 2y ago
Honestly it looks fun
saagarjha 2y ago
It’s fine if you swallow one. If you swallow two or more then you should probably go to the ER immediately.
plowjockey 2y ago
I probably didn't state that all that well. If I had really wanted one I'm sure I would have been provided one. It's equally quite possible that since they had to be obtained from a veterinarian that it never occurred to me to ask for one. OTOH, I did destroy a couple of old radios to get the speaker magnets. If I could go back in time I'd grab those old radios before I'd have a chance to destroy them. Back then they were just that--old radios--with no value and certainly not worth fixing. Sigh...

gumby 2y ago

> Many feed wagons have strong magnets under the discharge chute.. Even though I understand it's 1/r^2 this summoned a vision of a cow magnetically stuck to the discharge tube at her neck, with the head pushed up and mooing unhappily.

marcosdumay 2y ago
I think the force is actually 1/r^4. The magnetic field is proportional to 1/r^3. But the linear force is not proportional to it. (Rotations are.)
- planede 2y ago
  It's 1/r^4 for magnetic dipoles, where both have fixed a fixed dipole moment. So it's 1/r^4 between two permanent magnets. Where one object is a permanent magnet and the other is some unmagnetized ferromagnetic/paramagnetic piece metal, then the dipole moment of that piece of metal also depends on the distance. Assuming it's proportional to the magnetic field of the other dipole (~1/r^3) then the force is going to be ~1/r^7 for this pair of objects.
  - marcosdumay 2y ago
    Oh, that's right. But magnetization is famously path-dependent, so now I'm tending to believe the force will be closer to 1/r^7 when moving on the direction of the magnet, but 1/r^4 when moving away. And not exactly any of those functions.
    - planede 2y ago
      Do you mean that the ferromagnetic material gets magnetized and retains some magnetization while moving away?
      - marcosdumay 2y ago
        Yes.

SubiculumCode 2y ago

Got one once. Nice strong magnet with an odd shape....you can just imagine it going down the gullet.

peterleiser 2y ago

That's too bad. My parents were farmers and my dad brought some home one day, even though we no longer had cattle when we lived on our ranch. He thought I'd like to play with them, and he was right! Even my friends who weren't from farm families thought they were cool. I'm going to order some for my kids. These were the classic ones in the 1980's: https://en.m.wikipedia.org/wiki/Hardware_disease#/media/File%3ACowMagnet.jpg https://en.m.wikipedia.org/wiki/Hardware_disease#/media/File...

dehrmann 2y ago
My grandparents had a dairy, and growing up, I remember these on one of their filing cabinets. When I saw "cow magnets," I knew exactly what to expect.

wyclif 2y ago

Alnico magnets are the same type of magnets used in vintage electric guitar pickups.