Brazilian Journal of Veterinary Research and Animal Science; Vol. 45 Núm. 2 (2008); 87-94 Brazilian Journal of Veterinary Research and Animal Science; Vol. 45 No. 2 (2008); 87-94 Brazilian Journal of Veterinary Research and Animal Science; v. 45 n. 2 (2008); 87-94 Brazilian Journal of Veterinary Research and Animal Science; V. 45 N. 2 (2008); 87-94 Brazilian Journal of Veterinary Research and Animal Science Faculdade de Medicina Veterinária e Zootecnia da Universidade de São Paulo (FMVZ-USP) instacron:USP