Glass Bolus Research Articles

Effect of soluble-glass boluses on the copper, cobalt and selenium status of sheep

A soluble glass which has the trace elements copper, cobalt and selenium as part of its structure has been devised by Telfer et al. (1983). This soluble glass is manufactured by Pilkington Brothers and marketed by the Wellcome Foundation under the registered tradename of COSECURE. The COSECURE soluble glass is designed so that it can be given orally to ruminant animals such that when swallowed by the animal, the glass bolus will lodge within the reticulo-rumen of the animal and dissolve in a controlled fashion, thus making the trace elements copper, cobalt and selenium available to the animal. These glasses have been designed for use in both sheep and cattle. The cattle and adult sheep glasses will be effective for I year while the bolus for lambs is designed to be effective for up to 6 months. The trial reported here was carried out on Swaledale lambs, each lamb being given a single lamb-sized bolus of COSECURE at 7-8 weeks after birth. The effect of the COSECURE treatment was monitored by measuring several biochemical variables in the blood of the lambs and comparing these values with a group of untreated lambs. The liveweight gain of the lambs was also measured. The results of this experiment are given in Table 1 and show the response in the lambs blood on the copper status (plasma copper, plasma caeruloplasmin, and erythrocyte superoxide dismutase activity, cobalt status (serum vitamin B, ?) and selenium status (erythrocyte glutathione peroxidase activity). The differences between the treated and control lambs were significant at up to 150 days after treatment except for erythrocyte superoxide dismutase at 150 days. The liveweight gains of the treated lambs were also significantly greater than those of the controls ( 1 2.4 kg in treated as against 8.6kg in control, P<O.OOI). The use of soluble glasses containing trace elements as implants in animals has been reported by Allen et al. (1979) to be an example of a controlled-release system with a possible biological use. Work by Telfer & Zervas ( 1 982) and Telfer et al. (1984) has shown that soluble glasses in the form of rumen boluses can also be used in ruminant animals. The development of a suitable glass for the administration of several trace elements in one bolus by Telfer et al. (1983) has produced a product which will prevent or cure deficiencies of trace elements in cattle and sheep. The results reported here have shown that in the control lambs produced on one farm there were indications of marginal copper status, marginal selenium status and vitamin B , * deficiency at the various times of sampling. The effect of the treatment with the soluble-glass COSECURE was such as to elevate the blood status of the treated lambs in respect of copper, cobalt and selenium such that at 57 and 150 days after treatment these lambs could be taken as having a normal copper, cobalt and selenium status. Therefore soluble glass in the form of a rumen bolus will provide a controlled release of trace elements over a long period of time.