Haemato-chemical and immune variations in Holstein cows at different stages of lactation, parity, and age

Physiological components are influenced by various factors. However, little is comprehensively understood about lactation, parity, and age-related blood profile changes in dairy cows. Thus, we investigated significant variables associated with haemato-chemical and immune changes in healthy dairy cows. Blood was collected from 246 Holstein cows to analyse the physiological changes at different stages of lactation, parity, and age. The white blood cells (WBCs) and monocytes were influenced by the parity or age. Cows over three years of age showed a decreased WBC and monocyte count when compared to cows under three years of age. The lactation stage affected the red blood cell (RBC) profiles and metabolism, liver function-related components, and immunoglobulin A (IgA). A decrease in the haemoglobin (Hb) and haematocrit (HCT) were associated with peak lactation. The blood urea nitrogen (BUN) and total cholesterol (T-CHOL) concentrations, and alanine aminotransferase (ALT) and gamma-glutamyltransferase (GGT) activities increased in peak or mid lactation and remained high up to late lactation. An increased serum IgA concentration was observed in early and mid-lactation compared to that in late gestation. Many components of the haemato-chemical and immunological profiles changed (Hb, HCT, BUN, T-CHOL, ALT, GGT, and IgA) at a specific lactation stage under the physiological conditions. These data revealed that the lactation stage was a major variable contributing to the physiological variations in the dairy cows. Therefore, the lactation stage should be considered when determining haemato-chemical and immunological abnormalities.