Just a thought - I've never done it because as said, I don't buy it now - but you could try sprouting it for them.
Further to my first reply, plenty of people
do feed whole barley as part of their birds diet, I just don't as when starting out I made up a mixed feed and the birds didn't get on well with it, looking into it I was told it could set up an irritation in the crop so I never bought it again after that.
Best wishes.
