Multi-element assay of mammary secretions and sera from periparturient mares by inductively coupled argon plasma emission spectroscopy.

OBJECTIVE

To document and determine changes in the mineral profiles of sera and mammary secretions from a population of periparturient mares.

ANIMALS

18 clinically normal periparturient Arabian broodmares.

PROCEDURE

Inductively coupled argon emission spectroscopy was used to measure Ca, Cu, Fe, K, Mg, Mn, Na, P, and Zn concentrations in sera and mammary secretions of periparturient mares. In addition, S was measured in mammary secretions.

RESULTS

Serum concentrations of Ca, Cu, Fe, K, Mg, Na, P, and Zn remained constant throughout late pregnancy and the first 7 days of lactation. Compared with values on day 11 before foaling, mammary fluid concentrations of Ca, Cu, K, Mg, P, S, and Zn increased prior to parturition and all element concentrations, except Ca, decreased with the onset of lactation. In contrast, Na concentrations in mammary secretions decreased precipitously as parturition approached. Iron concentrations in mammary secretions remained relatively constant up to the time of parturition, decreased at parturition, and remained constant during lactation.

CONCLUSIONS AND CLINICAL RELEVANCE

Prior to foaling, increasing concentrations of Ca, Cu, K, Mg, P, S, or Zn in mammary secretions in concert with precipitous decreases in Na concentrations may provide a predictive index of impending parturition in the mare and a means of assessing fetal readiness for birth.