records books are everything chicken related. individual histories of the birds, their health, their parentage, their offspring. who they were bred to, did they get sold, did they die, did they have faults or strong points? wha was their band number, toe punch, wing band? their color? were they a cross? did you buy them? from who and how much? what did they weigh? gender? eye color, earlobe, legs, spurs, beak?
stuff like that, just to give u a start. all depends on how thorough u want to be.