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Zinc, cobalt and selenium are essential trace elements for ruminants and all have roles in immune function. The delivery of these elements to grazing livestock can be problematical. The aim of this trial is to determine the effect of the administration of an intraruminal soluble glass bolus to supply zinc, cobalt and selenium to growing lambs at pasture and to determine the effect on humoral immune response via the administration of a novel keyhole limpet haemacyanin (KLH) antigen. On days 0, 17 lambs each had a zinc (15.1% w/w), cobalt (0.52% w/w) and selenium (0.15% w/w) soluble glass bolus (∼33 g) administered (bolused), whilst the 17 lambs received no bolus (control). All of the lambs were grazed together throughout the trial. Trace element status (selenium—erythrocyte glutathione peroxidise activity; cobalt—serum vitamin B12 concentration; zinc—plasma zinc concentration) and live weights were assessed on days 0, 20, 42 and 63, with immunisation with KLH on day 34 and assessment of IgG response by direct ELISA on days 20, 42, 49, 63. Lambs were slaughtered when commercially fit on either day 86 or 121 and livers analysed for copper and zinc concentrations and boluses recovered from the bolus group to assess dissolution rates. The bolused lambs had significantly increased serum vitamin B 12 concentrations ( p p p p p p In conclusion, administration of a zinc, cobalt and selenium soluble glass bolus resulted in an increased antibody response and fulfilled the daily requirements for cobalt, selenium and zinc with an elevated status of these elements compared to unsupplemented controls grazing the same pasture. |
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