[Variations in plasma components in lactating mares at late pregnancy-early lactation (author's transl)]

In an experiment comparing pregnant then lactating mares with dry non-pregnant mares, the changes in plasma components were studied as indicators of the metabolic utilization of energy (glucose, non-esterified fatty acids, beta-hydroxybutyrate), nitrogen (urea, proteins) or minerals (calcium, phosphorus, magnesium). The mares were fed daily 2 kg concentrate and hay ad libitum. Beta-hydroxybutyrate, magnesium and to a lesser extent glucose were the only constituents whose levels were affected within the period starting one month before and ending one month after foaling. The increase in food intake between late pregnancy and early lactation may be explained by an increase in nutrient requirements, since plasmatic levels of non-esterified fatty acids and urea, known to be indicators of body lipids mobilization and nitrogen status respectively, remained constant.