ABSTRACT
OBJECTIVE: To determine reference ranges for hematologic and serum biochemical variables of bulls residing at an artificial insemination center. ANIMALS: 225 healthy Holstein bulls categorized by age into yearling, intermediate age, and adult groups. PROCEDURE: Hematologic and serum biochemical analyses were performed on 1 blood and 1 serum sample from each bull. RESULTS: Significant differences associated with age were identified for 25 of 33 variables. Serum creatinine concentration for clinically normal adult bulls (2.44+/-0.33 mg/dl) was higher than previously reported reference values for adult cattle. There was a reversal of the segmented neutrophil-to-lymphocyte ratio between yearling (0.85:1) and adult (2.6:1) bulls. This was associated with a significant and marked decrease in absolute numbers of lymphocytes per microliter between yearling (5,801+/-1,683) and adult (1,307+/-509) bulls. CLINICAL RELEVANCE: Reference values for selected clinicopathologic variables were generated from the data.
