There are many reasons that barley gets down graded to F1 or feed type barley, it should be still fit for human consumption as long as its been handled correctly.
I have been down graded to feed grade in the past because of an over supply of malt grade in the market and the buyers just dont need to pay the extra for the grain and they know that most farmers cant store shitloads of grain themselves until markets improve.
I use my own unmalted grain or that of my neighbours in some of my brews but I have a good idea of the protien content due to paddock history and fert applications.
All grain recieval sites have testing facillities and could tell you if your grain was F1, F2 or malting grade, I used to commonly take small samples of grain to be tested to them because if it doesnt make malting grade its actually more lucrative to sell it to a local farmer as feed grain rather than recieval sites.
I have been playing around with malting lately but drying/kilning the grain is a PITA and would require some equipment when doing more than a few killos, I tried to malt about 50-100 kg and the germination side was easy, the drying not so.
I would be looking to buy the grain off a farmer where you can ask questions re its storage and handling re chemical useage and buy a good quantity so you can maintain consistency. Look for a good sample of consistant sized grains without stain and with out too many other contaminants eg other seeds or insect debris.