Salt Lick Storage...
 

I'm not a dairy farmer, so I don't know, but, are salt licks always stored in a meat locker?

You can get them for dogs too. They don't need refrigeration, so I think they're just there because the St. Johns didn't have anywhere else to put them and the designers needed a salt lick in the scenario.

One advantage of storing the salt in the meat locker would less moisture in the air.

I'm not a farmer (I'm urban as my virtual counterpart would say) but storing your salt licks in a meat locker keeps dirt and debris away so the animal doesn't get sick eating dirt along with the minerals.