Serum vitamin D3 (25-OH vit D3) concentrations and hemogram changes in calves with enzootic pneumonia

Background: Enzootic pneumonia is an important disease complex associated with insufficient colostrum intake after birth, adverse environmental conditions, and stress. Vitamin D deficiency may be an important predisposing factor for this disease. Objective: This study aimed to investigate in calves with enzootic pneumonia. Methods: A total of 30 calves, aged 3-5 months, under the same care and feeding conditions were used. Groups were formed according to Clinical Respiratory Scoring as the group with mild/moderate enzootic pneumonia (n = 10), the group with severe enzootic pneumonia (n = 10), and the healthy control group (n = 10) without any disease. Blood samples were collected from the jugular vein of animals in all groups on Day 0; a complete blood count was performed, and serum vitamin D levels were measured using the Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) method. Results: Although no statistical differences were observed in total leukocyte, lymphocyte, eosinophil, basophil, hemoglobin, and hematocrit levels between groups, statistically significant differences in blood neutrophil, monocyte, and erythrocyte counts were found between the groups. Monocyte counts were statistically decreased in the mild/moderate group compared with the control group. Neutrophil counts were significantly higher in the mild/moderate and severe groups than in the control group. Erythrocyte counts were increased in the mild/moderate and severe groups compared with the control group. Vitamin D concentrations were statistically lower in the mild/moderate and severe groups than in the control group. However, no statistical differences in Vitamin D concentrations were observed between the mild/moderate and severe groups. There was a negative and significant correlation between erythrocyte counts and vitamin D concentrations (r = -0.64, P < .0001). While erythrocyte counts increased in the severe group compared with the mild/moderate group, vitamin D concentrations decreased. Also, a negative and significant correlation was observed between platelet counts and vitamin D concentrations (r = -0.74, P < .0001). Conclusions: The results of this study determined that serum vitamin D concentrations in calves with pneumonia were lower than those in healthy calves. Detailed studies on the etiologic and prognostic importance of low vitamin D levels in calves with enzootic pneumonia may provide valuable data for prevention and treatment.