The manuscript submitted here has undergone a round of review by AgResearch Scientists, including authors Neil Wedlock and Peter Janssen.  Amalgamation of  data in some figures may be done as the manuscript is further refined for publication. These changes will be relatively minor and will not alter the conclusions stated in this version of the manuscript. The final manuscript will then be subjected to further internal peer-review in the AgResearch system out-put release system prior to sending off to the journal.