I don't know that it was that you were feeding dog food. I think it was that it was Old Roy dog food. I wouldn't feed that stuff to my dog let alone my chicks.
Mine loose their little minds over chopped up hard boiled eggs. Honestly it's the funniest thing ever. Now I can put some in my hand and they all run over shoving everyone out of the way to get a bite. One of them (the quietest one normally) will even now jump right into my hand and sit there...