1. Section of Reproduction; Faculty of Veterinary Science; University of Pretoria; South Africa
2. Summerhill Stud; Mooi River South Africa
3. Moutonshoek; Piketberg South Africa
4. Equine Research Centre; Faculty of Veterinary Science; University of Pretoria; South Africa
5. Department of Equine Sciences; Faculty of Veterinary Medicine; Utrecht University; The Netherlands