Cheers Kevin, think you found what I was looking for! I've sent them an email.
At one of our monthly Beek meetings we had a Dr Sheba Khan from ANU & UC come and speak to us about her doctorte studies on bee bacteria, chalk brood and the development of pro biotics for them. It was really interesting to listen to! While she was there she motioned hygienic breeders (in WA I think) that were freezing a measured section of brood and then seeing what percentage the bees removed in a given period as a measure of their hygienic behavior and then breeding only from those hives that got 100% I think. Really cool stuff! (excuse the pun :-P)