...... No interaction was found between storage time and pre-warming profile for hatchability and chick quality....so a null result.
Since this is a summary of a paper, and not a full paper, I think that sentence is taken out of context, and is referring to no difference between the pre-warmed chicks and the control. I've also found two other papers supporting this technique, although both of them refer to the 4h and 24h warming and not the 30 minutes.