Abstract #M74

# M74
Metabolic stress biomarkers in dairy cows during early involution.
Lorraine M. Sordillo*1, Ashely Putnam1, Jennifer Brown1, Jeffery C. Gandy1, 1Michigan State University, East Lansing, MI.

Metabolic stress occurs in dairy cows when physiologic homeostasis is disrupted as a consequence of aberrant nutrient metabolism, chronic inflammation, and oxidative stress. Early lactation cows that suffer from metabolic stress are susceptible to health disorders that cause significant production losses. There is little information, however, regarding the occurrence and impact of metabolic stress during involution. The purpose of this study was to investigate well-known metabolic stress biomarkers at various time points during the early dry period when dairy cows are subjected to dramatic changes in physiologic homeostasis. A descriptive study was performed by collecting blood samples from the coccygeal vein of 27 healthy dairy cows at a commercial dairy herd. Sampling points were d −6, d 0, d +1, d +2, d +6, and d +12 relative to dry-off date. Serum samples were utilized to quantify biomarkers related to metabolic stress, including calcium, cholesterol, nonesterified fatty acids, β-hydroxybutyrate, albumin, haptoglobin, cortisol, reactive oxygen species, antioxidant potential, oxidative stress index, and isoprostanes. Data were checked for normality in SAS and analyzed by one-way ANOVA with Tukey’s adjustment for multiple comparisons. Within altered nutrient metabolism biomarkers, calcium and NEFA concentrations changed most from d 0 to d +2 during the sampling period. Haptoglobin is a biomarker of inflammation that gradually increased during involution with highest concentrations observed at d +12. In contrast, concentrations of albumin, a negative acute phase protein, were significantly lower at d +12 compared with other sampling points. All indicators of oxidative stress generally increased throughout most of the sampling period, suggesting altered oxidative stress states throughout early involution. Therefore, many of the biomarkers associated with metabolic stress changed during the transition from late lactation to the early dry period, but not to the same magnitude and duration reported previously in periparturient cows. Future studies should be directed toward assessment of other metabolic stress biomarkers and their effect on dairy cattle health and well-being during involution.

Key Words: metabolic stress, involution, inflammation