This work was carried out to evaluate the recombinant bovine somatotropin effect (rBST - BST analogous, commercially obtained by recombinant DNA technique), on hematological aspects (hematocrit, erythrocyte, hemoglobin, leukocyte, neutrophil, eosinophil, lymphocyte and monocyte) and metabolites (glucose, insulin, IGF-I, triglycerides, total cholesterol and urea) in heifers blood. Twenty-four crossbred heifers were used (½ Nellore x ½ Red Angus), they were approximately 18 months old and 225 kg of average body weight. All animals were fed with corn silage, citrus pulp and soybean meal during 84 days. 250 mg of rBST were administered subcutaneously, by intradermic way in the ischiorectal fossa. Treatments were: 1) control (administration of two mL of saline solution); 2) Single dose and 3) one dose each 14 days. The animals were used in a completely randomized design, with three treatments and eight replicates. The blood collect was realized in the beginning of the experiment and in the days 28, 56 and 84 of the experiment to determine the hematological aspects and metabolites. There was no influence of the rBST treatment on hematological aspects in the beginning and at the end of the experiment. However, the collect day had a positive linear effect on the hematocrit levels, negative linear on the glucose and triglycerides levels and positive quadratic on the IGF-I and urea levels. Also, the collect day effect was not observed on the insulin and total cholesterol levels.
feedlot; heifers; hematological parameters; bovine somatotropin
