the effect of selenium administration on the selenium, copper, iron and zinc status of pregnant heifers and their newborn calves

this study was performed to determine the effect of injecting selenium into pregnant heifers at the last stage of gestation on the serum se, cu, zn and fe status of the heifers and their calves. fifty holstein heifers were randomly assigned to one of five treatments. four and two weeks before the expected time of calving, the heifers were injected intramuscularly 10 ml (t1), 20 ml (t2), 30 ml (t3), 40 ml (t4) of selenium and vitamin e, respectively. the control (c) group received no supplement. each ml of the supplement© (vet. anim. health bv) contained 0.5 mg se as sodium selenite and 40 iu of d-l alpha-tocopheryl acetate. blood samples were collected from heifers two weeks before the expected time of calving and on calving day. blood samples of newborn calves also were taken from the jugular vein at birth and 7 days of age to measure the se, cu, zn and fe concentrations. the results indicated that the serum concentrations of se increased in treated heifers compared with the controls. the selenium concentrations were significantly increased in the colostrum of treated heifers (p< 0.05). zn concentration of both serum and colostrum decreased in the treated group compared with controls but it was not significantly different. serum se, cu concentrations of calves of treated heifers increased during the first week of age but the serum concentration of zn decreased in newborn calves at 7 days of age (p< 0.05). it seems that a high se injection (t4) in pregnant heifers could increase the cu and decrease the zn concentrations and, thus, might disturb the zn:cu ratio which, in turn, leads to zinc reduction in heifers and their newborn calves. it can be concluded that a higher amount of zn should be supplemented when more than 40 ml se supplements are administered to pregnant heifers.