Interpreting laboratory results from large animals is challenging owing to a lack of detailed reference ranges by age, sex, season, and breed. This study determined reference ranges for bovine serum chemistry and complete blood cell count (CBC) according to Holstein milking-cow age. Seventy-two healthy Holstein calves and cows (<1 week to milking age) were grouped: 1 (n = 7, <1 week), 2 (n = 10, 1 month), 3 (n = 13, 3 months), 4 (n = 13, 6 months), 5 (n = 10, 1 year, nulliparous), and 6 (n = 19, milking cows, parous). Fresh blood samples were obtained from the jugular vein between 10:00 and 12:00 AM in the winter; serum chemistry and haematologic profiles were assessed. Serum chemistry and CBC differed significantly by age. Age-related differences were observed for albumin, alkaline phosphatase, creatinine phosphokinase, creatinine, gamma-glutamyl transpeptidase, glucose, aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, magnesium, phosphorus, calcium, total bilirubin, total cholesterol, total protein, triglyceride, blood-urea nitrogen, non-esterified fatty acid, and beta-hydroxybutyric acid levels. Age differences in creatinine and C-reactive protein were not noticeable. Among CBC parameters, age-related differences were observed for white-blood-cell, lymphocyte, red-blood-cell, and platelet counts; hemoglobin level; haematocrit; mean corpuscular volume, mean corpuscular hemoglobin, and mean corpuscular-hemoglobin concentration. Therefore, age-dependent variations should be considered when interpreting cattle laboratory results.
Keywords: Holstein cattle; age-dependent variations; biochemistry; complete blood cell count; peripheral blood.