1. Departamento de Medicina Veterinária Preventiva e Reprodução Animal; FCAV, UNESP-Univ Estadual Paulista; Jaboticabal; SP; Brazil
2. ThomSon Mass Spectrometry Laboratory; UNICAMP; Institute of Chemistry; University of Campinas; Campinas; SP; Brazil
3. Dalton Mass Spectrometry Laboratory; UNICAMP; Institute of Chemistry; University of Campinas; Campinas; SP; Brazil
4. Department of Surgery; Division of Urology; Human Reproduction Section; Sao Paulo Federal University; Sao Paulo; SP; Brazil
5. Dipartimento di Scienze Veterinarie per la Salute; la Produzione Animale e la Sicurezza Alimentare; Università degli Studi di Milano; Milan; Italy