1. Farm Animal Practice, Royal (Dick) School of Veterinary Studies, University of Edinburgh; Easter Bush Roslin Midlothian EH25 9RG UK
2. Division of Reproduction; Department of Clinical Sciences; Swedish University of Agricultural Sciences; P.O. Box 7054 Uppsala SE-750 07 Sweden
3. Gård & Djurhälsan, Kungsängens Gård; Uppsala SE-753 23 Sweden