Homebrewing - Beer, Mead, Wine, Cider

A lot of feed variety barley is actually a malt style 2 or 6 row barley that just didn't make grade. Malt varieties are simply chosen for their traits to be more efficient at what all barley can do, which is to add sugars and enzymes to the wort. I grow "malt" varieties like Sirish and Synergy but I don't expect to make malt, and frankly, I don't even bother because the premium if it made germination and low protein levels is not high enough to delay getting it sold. But those varieties have good production and other harvesting traits I like.

I have malted our own barley and it works fine. Some things to look for are ergot; get all the black stuff out that you can, which will also get rid of stones and mildewed kernels. Ergot isn't something you want to brew with, since it can produce a hallucinogen. Also, the less mildew in it, the less likely you will get molding when you malt. High protein that you might find in a feed grade just makes it more effort to clear the beer afterwards but a lot of styles don't care, and if you do you can whirlfloc it or filter it.

Overall, I will say it's hardly worth the trouble. At least where I am, I can get a sack of 2-row malt for about a buck a pound and that will do a few 5gal brews. It's not really a large factor in the cost of a beer when it comes down to it. And malting takes up a lot of space and time.

Edit: and just to be clear, after I read the other comment: you do know you have to malt barley before you can brew with it, right? Because just dumping unmalted barley into a brew isn't going to give you beer.