1. Department of Veterinary Surgery and Medicine, Ahmadu Bello University, P.O. Box 720, Zaria, Nigeria
2. Department of Veterinary Public Health and Preventive Medicine, University of Ibadan, P.O. Box 720, Ibadan, Nigeria
3. Department of Veterinary Public Health and Preventive Medicine, Ahmadu Bello University, P.O. Box 720, Zaria, Nigeria
4. Animal Reproduction, Unit Jigawa Research Institute, 2646 Kazaure, Nigeria