Glucose Infusion Modulates Hematological Parameters in Postpartum Dairy Cows With and Without Clinical Metritis

Abstract

The early postpartum period is a critical window of metabolic and immunological vulnerability in dairy cows. This study evaluated the effects of intravenous glucose infusion on hematological parameters in cows with or without clinical metritis, using the intravenous glucose tolerance test (IVGTT) as a metabolic challenge. The experiment was conducted at the INIA La Estanzuela experimental dairy farm (Uruguay) with 45 Holstein cows evaluated at an average of 10.3 ± 1.65 days postpartum. Animals were classified using Metricheck®: cows with scores 2–3 were assigned to the metritis group (MET; n=20), and those with scores 0–1 to the healthy group (SAU; n=25). Within each group, cows were randomly assigned to receive glucose (GLU; 0.3 g/kg BW of 50% dextrose) or placebo (PLA), forming four experimental groups. Blood samples were collected before and after the IVGTT (day 10 ±1,65) and again on day 14. Data were analyzed using a repeated measures analysis of variance model with a factorial structure of group × treatment × time, using Statistix 10.0 software. Glucose infusion increased total leukocyte (WBC) counts (11.30±0.50 vs. 9.50±0.40×10⁹/L; p=0.0412) and neutrophils (NEU) (5.07±0.36 vs. 3.85±0.30×10⁹/L; p=0.0396) compared to placebo. Time effects were observed for NEU (p=0.0009), monocytes (p=0.0421), and eosinophils (EOS) (p=0.0005), with peaks in MET+GLU cows. The MET group showed lower EOS counts (0.18±0.02 vs. 0.27±0.03×10⁹/L; p=0.0279). Group × time interactions were significant for WBC (p=0.0003) and NEU (p<0.0001). After IVGTT, SAU cows showed the highest WBC (16.16±3.98×10⁹/L) and NEU (10.19±3.10×10⁹/L), while MET cows had 7.80±3.37×10⁹/L and 3.19±2.40×10⁹/L, respectively. No significant differences were found in red blood cell parameters (p>0.05). Glucose infusion during IVGTT modulated leukocyte profiles in postpartum cows, indicating that substrate availability influences innate immune activity. Metritis altered hematological responses independently, reinforcing the interplay between metabolic and inflammatory status in early lactation.