Background:Teefectsofpropolissupplementationontheperformanceofdairycalvesarenotwellestablished.Tisstudyaimed to investigate the efects of oral propolis supplementation on the health status, growth performance variables, hematological parameters, and serum biochemical parameters of neonatal dairy calves. Methods: Twenty-four calves were enrolled in this study from 48h after birth until 7days of age. A complete clinical examination was performed daily by the same examiner. Blood sampling, body measurements, and lung ultrasonography were conducted on Days 0, 7, 14, and 28. Te concentrations of albumin, total protein, total immunoglobulins, γ-globulins, triglycerides, total cholesterol, urea, creatinine, inorganic phosphate, and the activities of aspartate aminotransferase, alanine aminotransferase, and gamma-glutamyl transferase were measured. Results: Propolis supplementation had no signifcant efect on body weight, average daily gain, length, or height (p>0.05). Pulmonary ultrasonography scores for subclinical pneumonia showed signifcant variation over time within each group (p<0.05); however, no signifcant diferences were observed between groups. Propolis supplementation signifcantly reduced the number of days with omphalitis in neonatal calves, likely due to its known anti-infammatory and antimicrobial efects, although further studies are needed to clarify the underlying mechanisms (p � 0.016). Tere were no signifcant diferences in the number of days with fever or diarrhea between groups (p � 0.44 and 0.15, respectively). No signifcant diferences were found in blood variables between groups. Our results suggest that propolis supplementation did not positively afect growth performance or blood variables. Conclusion: Supplementation with propolis may be benefcial in reducing the incidence of omphalitis in neonatal dairy calves. Nevertheless, further studies are required to fully elucidate the efects of propolis.

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