Changes of iron, zinc and copper in the blood plasma of Holstein mares during gravidity and early lactation.

This study has been made on six Holstein breed mares aging from 5 to 10 years. During gravidity and in early lactation blood for analysis was taken three times by venepuncture performed on the jugular vein with heparin as anticoagulans. The blood was taken on three occasions during the gravidity: within the first third of gravidity (till 15th week), the second third of gravidity (between 16th and 30th week) and the last trimester (from 31st week till a foaling). The last sampling was during early lactation. The blood plasma was separated by centrifugation at 1500 g for 15 minutes. The concentration of the minerals in blood plasma has been determined spectrophotometrically by a commercial set. The concentration of iron during the period of gravidity and lactation showed a continual decrease of the average values. The highest values are measured in the beginning and the lowest in the period of early lactation. There was no significant difference in the iron concentration determined between the research periods. In the second third the concentration of copper decreased and represented the lowest average value during the gravidity in mares. In the last stage of the gravidity there was noticed a significant increase of the concentration of copper in blood plasma. Such a significant increase continued during the period of early lactation when the highest values were measured. In the 15th week of gestation the measured concentration of zinc showed the highest value during the experiment and differed significantly front the concentration measured in the second stage of the experiment. The low values maintained till the end of the gravidity. According to the results of this study the changes of the concentration of minerals in blood plasma during the period of gravidity and early lactation are closely associated to inappropriate trace Mineral supplementation. That might cause the metabolic changes and related pathological states in mares and foals.