1. Animal Physiology and Phytopharmacology Laboratory, University of Dschang, Dschang, Cameroon;
2. Department of Animal Organisms Biology, University of Douala, Douala, Cameroon;
3. Laboratorio de Comportamiento Reproductivo, Escuela de Medicina Veterinaria y Zootecnia, Universidad Autonoma de Tlaxcala-Mexico, Tlaxcala, Mexico;
4. Department of Animal Biology and Physiology, University of Yaoundé, Yaoundé, Cameroon