Short communication: Reference intervals for serum biochemical parameters in dairy calves during the first 10 days of...

Accurate reference intervals for serum biochemical parameters are essential for clinical interpretation in neonatal calves, yet data for the first days of life remain limited and rarely stratified by narrow age ranges. This study established age-specific reference intervals for clinically healthy Italian Holstein-Friesian calves during the first 10 days of life and evaluated differences among three age groups (24-48 h, 3-4 days, 5-10 days). A total of 178 calves were enrolled. Serum samples were analyzed for indicators of liver function, muscle metabolism, energy metabolism, lipid profile, protein status, acute-phase response, and mineral balance. Nonparametric reference intervals were calculated for each age group. Most analytes were significantly influenced by age, except haptoglobin, total protein, and beta-hydroxybutyrate. Results highlight the dynamic physiology of the neonatal period and provide robust, age-stratified RIs to improve clinical decision-making and research interpretation in neonatal bovine medicine.