Changes of some serum minerals in pregnant Holstein Cattles in Birjand

Minerals are essential in reproduction، growth and metabolism. Since minerals are influenced by environmental and nutritional factors and have interaction with physiological status، their determination is valuable in relation to pregnancy. To do this، blood samples were taken from 100 Holstein cattle from different regions of Birjand، including 75 pregnant (light، moderate and heavy pregnant) and 25 delivered. Calcium، phosphorus، magnesium، copper، zinc، and iron were measured in the cattle serum. The levels of magnesium and copper were decreased significantly during the period of pregnancy (P<0. 05). Decrease of the calcium، phosphorus and zinc concentration during this period were not statistically significant (P>0. 05). The level of magnesium and zinc significantly (P<0. 05)، and the level of copper partially (P<0. 05) increased in delivered cows، but calcium reduction was potentiated in this group (P<0. 05). Ferrous was the unique element which partially increased during gestational period (P<0. 05). The reduction of minerals during gestational period specifically in heavy cattle may be related to the increased need of the mother and fetus، or the probability of minerals interaction.