No, it ain't junk.
Cattle will eat and crave salt.
They'll eat sticks and bones if they're short.
But most minerals taste bad. And cows won't eat them.
The so called 'smorgasboard'---where you put out the ingredients and they take what they want--is a joke.
With minerals---you got to have something in it to make them eat it---like salt, grain, etc.
And you gotta have something in it so they don't eat too much--like salt, phosphorous is bitter and used to be kinda a control but got too expensive.
so--it's a balancing act. And their consumption will change with their diet---not necessarily because their needs have changed.
I mix mine with loose salt. I make sure they're filled up on salt first, if they've run out. It's not recommended, I'm probably overfeeding a tad, I can get close to the 4 oz rec'd.
Since good mineral program, I have almost -o- dystocia and hardly ever have anything weird or malformed. Our calving assistance ---where somebody has hand inside a cow---is probably less than 1 in 200.
Good mineral is cheap. But---mineral is not something you buy on price. Know what you're getting and what ingredients are sourced from---some more expensive inputs are cheaper when you consider the efficiency.
In winter on rough feed, adding bovatec will pay all mineral and salt bills.