@ClemKadiddlehopper sort of funny, my neighbor had a dairy about 40 years. About dairy cattle he'd say "A Holstein is born looking for a place to die!". I learned I never wanted to buy a holstein.
I've never seen Calf Manna at the farm supply stores I shop. I checked their website, said TSC carried it. I checked both my local TSC stores. Neither carried it.
About protein... I can't get the little guy to eat cattle cubes (20%protein). The horse and donkey fight over them, good thing, I bought 300lbs.
The richest food I've gotten him to eat is 18% calf grower. Funny he'll take his nose and push the cattle cubes to one side and eat every scrap of the grower. The hay I got from my cousin just down the road, heavily fertilized Bahia grass.