Pilot Study: Exploring the Feasibility of Individual Voluntary Waiting Period Settings Using Postpartum Recovery Indicators in Dairy Cows

Abstract

This study aimed to identify hematological markers that can objectively assess postpartum recovery in dairy cows, which is essential for determining an individualized voluntary waiting period (VWP). Twenty Holstein cows were divided into early recovery and late recovery groups based on their clinical uterine recovery. Blood samples were collected from coccygeal vessels and analyzed for inflammatory and metabolic markers, including serum amyloid A (SAA), haptoglobin (HPT), cortisol (COR), substance P (SP), interleukin-6 (IL-6), total cholesterol (T-Chol), beta-hydroxybutyrate, and non-esterified fatty acids (NEFA). Both SAA and HPT significantly decreased after recovery compared to immediately after parturition (p < 0.001), whereas T-Chol and NEFA significantly increased and decreased over time, respectively, indicating recovery from a negative energy balance status. No significant changes were observed in COR, SP, or IL-6 levels. Thus, SAA and HPT are sensitive indicators of postpartum inflammation, whereas T-Chol and NEFA levels reflect metabolic recovery. Using these hematological markers enables a more objective and customized setting of VWP for each cow, potentially improving reproductive efficiency and farm profitability. Further studies are warranted to establish cutoff values for each parity and validate the applicability of individualized VWP models.