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Plasma alpha-1-acid glycoprotein concentration is associated with key blood biomarkers and disease incidence during the transition period.

W. E. Brown

M140
Plasma alpha-1-acid glycoprotein concentration is associated with key blood biomarkers and disease incidence during the transition period.
W. E. Brown*1, M. Garcia1, L. K. Mamedova1, K. R. Christman1, M. G. Zenobi2, C. R. Staples2, B. M. Leno3, T. R. Overton3, B. K. Whitlock4, J. A. Daniel5, B. J. Bradford1,6. 1Kansas State University Manhattan, KS, 2University of Florida Gainesville, FL, 3Cornell University Ithaca, NY, 4University of Tennessee Knoxville, TN, 5Berry College Mount Berry, GA, 6Michigan State University East Lansing, MI.

Alpha-1-acid glycoprotein (AGP) is an anti-inflammatory acute-phase protein which is negatively associated with feed intake in postpartum dairy cows. Our objective was to determine associations between AGP and other biomarkers in transition dairy cows, and to evaluate the utility of AGP for predicting postpartum disease risk. Plasma samples (n = 2,086) from 434 Holstein cows in 6 studies were analyzed for AGP, glucose, insulin, free fatty acids (FFA), β-hydroxybutyrate (BHB), and haptoglobin on d −21, −12 ± 3, −3, 1, 3, 7 ± 1, 14 ± 1, and 21 ± 1 relative to parturition. A model was constructed with linear and quadratic fixed effects of AGP, with random effects of treatment(study). Quadratic effects with P > 0.20 were removed. Nominal logistics were used to determine the association of AGP concentration with disease incidence using fixed effects of AGP and study. On d −12, AGP was quadratically associated with BHB (P = 0.02) and negatively associated with insulin (P = 0.04), and d −3 AGP was positively associated with d 21 FFA (P = 0.04). On d 3 and 7, AGP was positively associated with BHB on d 7 (P < 0.01). Haptoglobin and AGP were positively associated on d 3 (P < 0.001), d 7 (P < 0.001), and quadratically associated on d 14 (P = 0.02). On d −12, AGP was associated with postpartum incidence of retained placenta (RP; P = 0.05) and tended to be associated with milk fever (P = 0.06). Plasma AGP on d 3, d 7, and d 14 was highly associated with postpartum incidence of displaced abomasum (DA), RP, and metritis (P < 0.001). Receiver operating characteristics for the association between AGP and postpartum DA incidence on d 3 (P = 0.02), d 7 (P < 0.001) and d 14 (P = 0.05) were excellent, with area under the curve of 0.99, 1.0, and 0.93, respectively. Plasma AGP on d 1 (P = 0.06) and d 3 (P = 0.09) tended to be associated with retention to 280 d in milk. Despite significant associations between AGP and postpartum disease, its utility for disease forecasting was less promising. Nevertheless, limited associations between AGP and metabolic biomarkers suggest it may serve as a unique predictive variable.

Keywords: acute-phase protein, biomarker.