Universidade Federal do Paraná. Departamento de Medicina Veterinária. Curitiba, PR, Brazil.Universidade Federal do Pará - Campus Castanhal. Instituto de Medicina Veterinária. Castanhal, PA, Brazil.Universidade Federal do Pará - Campus Castanhal. Instituto de Medicina Veterinária. Castanhal, PA, Brazil.Universidade Federal do Sul e Sudeste do Pará. Instituto de Estudos do Trópico Úmido. Xinguara, PA, Brazil.Ministério da Saúde. Secretaria de Vigilância em Saúde e Ambiente. Instituto Evandro Chagas. Laboratório de Toxicologia. Ananindeua, PA, Brasil.Universidade Federal do Paraná. Departamento de Medicina Veterinária. Curitiba, PR, Brazil.Universidade do Estado de Santa Catarina. Departamento de Medicina Veterinária. Florianópolis, SC, Brazil.Universidade Federal do Paraná. Departamento de Medicina Veterinária. Curitiba, PR, Brazil.Universidade Federal do Paraná. Departamento de Medicina Veterinária. Curitiba, PR, Brazil.This study collected samples from 50 Holstein cows, most intensively bred, and from the Campos Gerais region, Paraná, with an average milk production of 30.21L/day. Samples of the liver, spleen and lymph nodes were collected to determine the levels of copper, cobalt, iron, molybdenum and zinc. Spleen and lymph nodes were subjected to histological analysis and evaluation of the degree of hemosiderosis. The average concentrations of copper (495.05ppm), molybdenum (4.19ppm), and zinc (274.49ppm) were higher than those established for the bovines. For cobalt 26% of the animals presented levels below the established level, which characterized cobalt deficiency. Only iron (299.12ppm) exhibited an adequate average level. Histopathologically hemosiderosis was observed mainly in the spleen (78%) and less frequently in the lymph nodes (20%). The observation of hemosiderin in the spleen and lymph nodes is not related to copper deficiency. Still it may be related to high levels of molybdenum, zinc, iron, or other undetermined causes
