Effect of a copper, cobalt and selenium soluble glass bolus given to grazing sheep

Three field trials were carried out to evaluate the performance of a sintered soluble glass copper, cobalt and selenium bolus for maintaining adequate levels of the three tract elements. Trial 1 used 34 growing lambs. trial 3 used 36 growing lambs whilst trial 3 used 50 year-old non productive female sheep. In each trial half the: sheep had a bolus administered (bolused) and half remained as controls. Blood samples were taken immediately prior to bolus administration and then at regular intervals throughout each trial. The samples were analysed for copper status (serum caeruloplnsmin activity and plasma copper concentration), cobalt status (serum vitamin B-12 concentration) and selenium status (erythrocyte glutathione peroxidase activity). For trial 1 the bolused sheep at all post treatment samplings (days 20, 42 and 63) were significantly increased in both cobalt and selenium status (P < 0.001) compared to the controls, however. there were no significant differences in any other blood parameter. For trial 1 liver copper concentrations were analysed on slaughter samples and were significantly increased for the bolused lambs (P < 0.001). In trial 3 the bolused sheep had significantly increased selenium and cobalt status (P < 0.001) for all samples (days 28, 51. 69, 91). In trial 3 the selenium status of the bolused sheep was significantly increased at all three samplings (day 21, P < 0.05 and days 51 and 105, P < 0.001), whilst the cobalt status was also significantly increased on all sample days (day 21, P < 0.05; day 51, P < 0.01 and day 105 P < 0.001). The sintered soluble glass copper, cobalt and selenium bolus was able to prevent or correct deficient and/or marginal cobalt and selenium status of sheep throughout these trials. The bolus had little measured effect on the already adequate blood parameters of copper status, although the liver copper concentrations of the bolused sheep were higher in the trial for which they were analysed. (C) 2001 Elsevier Science B.V. All rights reserved.