How do they keep it stocked on shelves then

I've never heard of store staff shaking the bottles. The bottle I have says it expires in 2013 thats kind of confusing lol. So I can hatch my own brine shrimp though I've got lots of eggs, would baby brine shrimp work? I havent hatched them in awhile though can I just use them straight from hatching cuz I have no idea how to wash them