| 摘要 |
A water soluble glass rumen bolus for treating a mineral deficiency in a ruminant animal has the following composition: a) P2O5 b) R2O where R is chosen from Na, K and Li c) at least one other glass forming or modifying material, usually CaO, MgO or Al2O3 d) at least one deficiency-rectifying element selected from Cu, Se, Co, Zn, I, Mn and Mg. In the composition the sum of P2O5 and R2O is not less than 56 mol%, and not more than 76 mol% if CuO and/or ZnO are present or not more than 92 mol% if CuO and/or ZnO are absent and one or more of CoO, SeO and I is present. If CuO and/or ZnO is present then the amount of each of P2O5 and R2O (preferably present in substantially equimolar amounts) does not exceed 45 mol%. The composition is such that when the bolus is lodged in the reticulo rumen, it has a release rate of not more than 25 mg per square centimetre of its surface area per day, so making possible boluses which can be administered to the animal to release the required element or elements over periods up to one year or more. |
