Reference values of the Urea and Creatine seric rates of Jersey breed, raised in the São Paulo State. The influence of age and sexual factors - Gregory, Lilian; Birgel Júnior, Eduardo Harry; Mirandola, Regina Mieko Sakata; Araújo, Wanderley Pereira de; Birgel, Eduardo Harry (Congreso Mundial de Buiatria, 2000)