Changes in biomarkers of metabolic stress during late gestation of dairy cows associated with colostrum volume and immunoglobulins content

Abstract

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 and Ig content. For this, healthy Holstein cows were randomly selected from 3 commercial herds in Michigan. In each farm, four cohorts of 21 cows (one per season), stratified by parity, were enrolled (n=228). 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 6 h of calving and the volume of colostrum produced was recorded and an aliquot collected. Concentration of IgG, IgA, and IgM were measured by radial immunodiffusion. Cows were grouped into high colostrum producer (HCP) or low (LCP), high IgG (HIG) or low (LIG), high IgA (HIA) or low (LIA), and high IgM (HIM) or low (LIM). For volume category, we arbitrarily defined 6 L of colostrum (4 L for first and 2 L for second feeding of calves) as the cut-off point, whereas for IgG we used the industry standard of [&ge;] 50g/L. To create groups of low and high IgM or IgA, we used the median of these Ig as the cutoff point. Colostrum volume was lowest in winter, but no differences were observed among parity groups. Conversely, colostrum IgG concentration was highest in fall and winter, but colostrum IgM was lowest at these seasons. However, colostrum Ig content only showed a negative weak correlation with volume (Spearman rho < -0.28). Compared to LCP, HCP cows had higher concentrations of antioxidant potential, BHB and lower cholesterol and oxidant status index. HIG cows showed higher concentrations of glucose compared to LIG. HIA cows had higher concentrations of cholesterol, reactive oxygen and nitrogen species, oxidant status index, and total protein, while BHB, and glucose were lower compared with LIA. Biomarkers of metabolic stress were not significantly different between HIM and LIM. Nevertheless, the differences observed did not result in differences in inflammatory status between animals in any of the colostrum variable categories analyzed, suggesting that physiological homeostasis was not disrupted during late gestation in association with the colostrum variables studied. Overall, the great variability observed in colostrum variables suggests that colostrogenesis is a complex and multifactorial process. However, our results suggest that greater availability of antioxidants during late gestation could support the production of higher volumes of colostrum, which needs to be explored in future trials. INTERPRETIVE SUMMARYChanges in biomarkers of metabolic stress during late gestation of dairy cows associated with colostrum volume and immunoglobulins content. By Rossi et al., page XXXX. We investigated associations between metabolic stress during the last 6 wk of gestation and the volume and immunoglobulin content of the colostrum produced. We observed that cows producing more than 6 L of colostrum exhibited increased metabolic activity during late gestation. Also, a greater blood antioxidant activity throughout late gestation was observed in cows with higher yields of colostrum, suggesting that greater availability of antioxidants might support the production of higher volumes of colostrum. Therefore, further studies should evaluate whether supplementation with additional antioxidants supplement during late gestation can improve colostrum yield.