[1] Univ Ibadan, Fac Vet Med, Dept Theriogenol, Ibadan, Oyo, Nigeria
[2] Univ Ft Hare, Dept Livestock & Pasture Sci, ZA-5700 Alice, South Africa
[3] Univ South Africa, Dept Agr & Anim Hlth, ZA-1710 Johannesburg, South Africa
[4] Univ Ibadan, Fac Vet Med, Dept Vet Biochem & Physiol, Ibadan, Oyo, Nigeria
[5] Univ Alabama, Coll Community Hlth & Sci, Dept Interdisciplinary Studies, Tuscaloosa, AL USA
[6] Univ Ibadan, Fac Vet Med, Dept Vet Pathol, Ibadan, Oyo, Nigeria