Affiliation: | Department of Veterinary Medicine, Pharmacology and Toxicology, University of Khartoum, P.O. Box 32, Khartoum North, Sudan;Department of Veterinary Surgery Obstetrics and Gynaecology, University of Khartoum, P.O. Box 32, Khartoum North, Sudan;Clinic for Andrology and Artificial Insemination, School of Veterinary Medicine, Hannover, Federal Republic of Germany |