1. Norwegian Veterinary Institute, P.O. Box 750 Sentrum, N-0106 Oslo, Norway
2. Chemistry Department, University of Waikato, Private Bag 3105, 3240 Hamilton, New Zealand
3. Department
of Chemistry, University of Oslo, P.O. Box 1033, N-0315 Oslo, Norway
4. AgResearch Ltd., Ruakura Research Centre, Bisley Road, Private Bag 3123, Hamilton 3240, New Zealand