Association between metabolic and immunological changes during the transition period of dual-purpose cows in the Veracruz tropic, Mexico

The objective of this study was to identify changes and associations in body condition score (BCS), serum glucose and β-hydroxybutyrate (BHB) concentrations, and white blood cell populations in dual-purpose cows during the transition period in the Veracruz tropic. BCS was evaluated and blood samples were taken weekly to determine white blood cell populations, serum glucose and BHB concentrations of 30 multiparous dual-cows (Bos taurus × Bos indicus) from 3 weeks before the expected date of calving to 3 weeks postpartum. During the prepartum period, BCS (3.56 vs 3.11 points), leukocytes (8.964 vs 7.032 × 10³ cells µL-¹), neutrophils (3.353 vs 2.201 × 10³ cells µL-¹), lymphocytes (4.750 vs 4.051 × 10³ cells µL-¹), and monocytes populations (222 vs 126 × 10³ cells µL -¹) were higher compared to the postpartum period. Contrarily, BHB concentration was higher in the postpartum period (1.34 vs 0.84 mmol L-¹) than in the prepartum period. No differences in basophils and eosinophils populations and glucose concentration were identified. Associations between BCS, BHB, glucose, and populations of neutrophils, monocytes, and basophils were detected. The higher BCS, the higher the monocyte population (r = 0.22). The lower the glucose concentration, the higher the BHB concentration (r = −0.51). The higher the concentration of BHB, the lower the number of neutrophils (r = −0.22), monocytes (r = −0.32) and basophils (r = −0.23). In conclusion, low-producing dual-purpose cows experienced fluctuations in BCS, BHB, and immune cell populations during the transition period, suggesting similar metabolic and immune changes as in high-producing dairy cows.