Variations in hematological parameters of Brazilian Bonsmara cattle at different stages of lactation

The aim of this study was to evaluate the hematological parameters of non-lactating Bonsmara cows and cows at different stages of lactation. A total of 119 cows were used, divided into four groups according to the number of lactations. The hematological evaluations performed were erythrogram and leucogram using automated equipment. The descriptive statistical analysis of the data was performed with a 5% significance level. The experiment followed the ethical principles of animal experimentation (CEUA-UFU protocol 053/2018). Significant differences were found in first lactation animals for erythrocyte count and in second lactation animals for erythrocyte count, hemoglobin, globule volume and platelets. In third lactation animals, significant differences were found for mean corpuscular hemoglobin concentration and platelets. In non-lactating animals, the mean corpuscular hemoglobin concentration showed a significant difference. For the leukogram, significant changes were found in the third lactation animals for rods; and in the concentration of total leukocytes and lymphocytes in the non-lactating animals. This study on the hematology of Bonsmara cattle can serve as a reference base for hematological parameters and as a stimulus for further research on the subject.