Brazilian Journal of Veterinary Research and Animal Science; Vol. 50 Núm. 1 (2013); 18-25 Brazilian Journal of Veterinary Research and Animal Science; Vol. 50 No. 1 (2013); 18-25 Brazilian Journal of Veterinary Research and Animal Science; v. 50 n. 1 (2013); 18-25 Brazilian Journal of Veterinary Research and Animal Science; V. 50 N. 1 (2013); 18-25 Brazilian Journal of Veterinary Research and Animal Science Faculdade de Medicina Veterinária e Zootecnia da Universidade de São Paulo (FMVZ-USP) instacron:USP