作者单位:University of Utrecht, Faculty of Veterinary Medicine, Department of Equine Science - Reproduction, Utrecht, The Netherlands[1]Boehringer Ingelheim Animal Health GmbH, Basel, Switzerland[2]SUISAG, Sempach, Switzerland[3]Boehringer Ingelheim Pharma GmbH & Co KG, BDM, Europe[4]University of Veterinary Medicine, Hannover, Germany[5]