Greetings Sue, from the Waikato.
My 14 year old computer is having issues with dial-up on very poor country telephone wires, continually interfered with by our numerous electric fence shorts so is dropping out. I'm checking email through family member cell phones so not really able to look up contact details, but if I was asking your question the first place I would be going is the Breed Societies. I believe there is still a SHORTHORN one on the go. Interested parties there should be able to advise you of past publications about your selected breed, and give you the pedigrees of named animals.
Some very expensive bulls were imported into the Waikato by the pioneers. I believe I have information about one on my WOODLANDS research file of several hundred pages.
The Kainui district Stoke's family near Taupiri, were the family that I last saw exhibiting SHORTHORNS. Agricultural & Pastural Show secretaries would also have breed society contacts.
- Alan