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Changes in biomarkers of metabolic stress during late gestation of dairy cows associated with colostrum volume.

R. M. Rossi




Changes in biomarkers of metabolic stress during late gestation of dairy cows associated with colostrum volume.
R. M. Rossi*, F. Cullens, P. Bacigalupo, L. M. Sordillo, A. Abuelo. Michigan State University East Lansing, MI.

The objective of this observational study was to compare the metabolic status of dairy cows during the last 6 wk of gestation based on colostrum volume. Healthy Holstein cows were randomly selected from 2 commercial dairy herds in Michigan. Two cohorts of 21 cows each, one for the summer and another for the fall of 2019, were enrolled in each farm with similar parity distribution. Cows were blood sampled weekly during the last 6 wk of gestation, and biomarkers related to nutrient utilization, oxidant status, and inflammation were quantified in serum. Cows were milked within 6h of calving and the volume of colostrum produced was recorded and an aliquot collected. For this study, only the data from 63 cows producing colostrum with IgG >50 g/L were considered to avoid confounding due to poor IgG content. Cows were grouped into high colostrum producer (HCP) or low colostrum producer (LCP). For that, we arbitrarily defined 6 L of colostrum (4 L for first and 2 L for second feeding of calves), as the cut-off point. Data were analyzed statistically through mixed models with repeated measures including the fixed effects of group (HCP vs. LCP), time, and their interaction; and the random effects of cow, lactation number, and farm. The HCP cows had higher β-hydroxybutyrate, blood urea nitrogen, magnesium, and lower glucose serum concentrations throughout the study period compared with LCP cows. Furthermore, HCP cows also showed higher concentration of reactive oxygen species compared with LCP cows, resulting in higher oxidant status index values despite no changes in antioxidant potential. No differences were found for haptoglobin, a biomarker of inflammation. Collectively, these data show that HCP cows had greater utilization of nutrients throughout the study period. Thus, indicating a higher metabolism activity, which might explain the elevation in markers of oxidant status. Nevertheless, the differences observed did not result in changes in biomarkers of inflammation or lipid mobilization, suggesting that physiological homeostasis was not disrupted in HCP cows during late gestation.

Keywords: oxidant status, colostrogenesis, passive immunity.