Citologia de medula óssea das primeiras seis semanas de vida de bovinos da raça Holandesa / Cytology of the bone marrow of the first six weeks of life of Holstein cattle

ABSTRACT

The possible changes in the bone marrow associated with hematological changes in peripheral blood during the first six weeks of life in cattle were evaluated. To this purpose, blood samples were evaluated at 2, 4, 7, 10, 14, 21, 28, 35, and 42 days of life, and cytologic examination of bone marrow at 2, 7, 21, and 42 days of life in 10 Holstein calves. The bone marrow examination showed, in different times, myeloiderythroid ratio from 0.60 to 0.69. The erythroid lineage distribution remained pyramidal, with concentration of precursor cells above the initial reference values for adult cattle. Proliferation pool of myeloid lineage also remained above the reference range, with decreases of concentrations in the third and sixth weeks. In the lymphoid lineage, the concentration of lymphocytes showed a decrease in the first three weeks, with a tendency to rise in the sixth week.