The retention and efficacy of soluble-glass boluses for providing selenium, cobalt and copper to sheep

Authors: Meads WJ, Millar KR, Scahill BG, Sheppard AD, Albyt AT
Publication: New Zealand Veterinary Journal, Volume 36, Issue 1, pp 11-14, Mar 1988
Publisher: Taylor and Francis

Animal type: Livestock, Production animal, Ruminant, Sheep
Subject Terms: Animal remedies/veterinary medicines, Cobalt/vitamin B12, Trace elements, Copper, Diet/rations/food, Treatment/therapy, Nutrition/metabolism, Poisoning - chemical, Selenium, Vitamins
Article class: Scientific Article

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Abstract: The efficacy and retention of prototype and commercial (Cosecure) soluble-glass boluses containing selenium, cobalt and copper and having a similar size, density and composition were evaluated in separate 12-month trials with sheep grazing low selenium pastures but with adequate cobalt and copper levels. In both trials, sheep confirmed by X-ray as containing a bolus grew at a significantly greater rate than control sheep. This was attributed to the correction of a selenium deficiency. Although liver copper, and liver and serum vitamin Br2 levels were significantly greater in treated sheep than controls on some occasions, the differences were not as great or consistent as with blood selenium levels. The rate of bolus loss was high and in both trials, approximately 40% of the sheep had lost the bolus after 6 months. No prototype boluses were present after 12 months. Intact Cosecure boluses were recovered from 3 sheep out of 30 after 12 months whilst one animal contained a part bolus. The recovered boluses were approximately 45% lighter than when originally administered. Bolus loss did not appear to be due to complete dissolution. In sheep which had lost the bolus, blood selenium levels fell with a half-life of 43 ± 10 days.

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