Downer cows and variations in the treatment response are of great interest to farmers. Positively responded animals get up at different extended periods after receiving the same treatment protocol. The objective of this study is to determine if there is any association between the duration of recumbency and the level of serum biomarkers. Serum samples from 165 crossbred Holstein dairy cows (105 downer cows of metabolic causes only and 50 healthy) and from 65 cured cows after treatment were used for analysis of calcium (Ca), inorganic phosphorus (P), potassium (K), magnesium (Mg), creatine phosphokinase (CPK), aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transferase (GGT), beta-hydroxybutyric acid (BHBA), non-esterified fatty acid (NEFA), and triglycerides (TG). Assessment of diagnostic performance of these biomarkers was performed using analysis of the receiver operating characteristic (ROC). Serum levels of Ca, P, K, and TG decreased significantly (P < 0.001), while CPK, AST, ALT, BHBA, and NEFA increased significantly (P < 0.001) in those downers compared with controls. They achieved high diagnostic performance in ROC curve analysis. Interestingly, 65 cows responded after treatment and stood up (cured cases) after a period of recumbency varying from 4 to 15 days and statistics revealed a significant association (P < 0.05) between those days of recumbency and only serum K levels. We concluded that only the serum potassium (K) level is a significant predictor of post-treatment recumbency period and that the serum P, CPK, and NEFA levels have the highest diagnostic performance.
Keywords: Downer cows; Metabolic disorders; Potassium; Prognosis; ROC analysis; Recumbency period.