Trace element nutrition of grazing ruminants. 2. Hepatic copper storage in young and adult sheep and cattle given varying quantities of oxidized copper particles and other copper supplements

Abstract

Hepatic copper (Cu) storage was determined by biopsy after oxidized Cu wire was given to sucking lambs at 0-43 days of age, and to weaned Merino sheep and Hereford cattle varying in age. Cu-calcium edetate (Cu-EDTA) and soluble glass pellets were also evaluated as Cu supplements. A dose of 45 mg oxidized particles/kg liveweight was predicted to induce a mean maximum response of 84 and 179 mg Cu/kg DM in hepatic concentrations in weaned Merino sheep and Hereford cattle at 49 and 100 days from dosing respectively; these responses should not result in unacceptable hepatic concentrations in cattle, or in sheep of low Cu status, but the response is variable, and supplementation as a precautionary measure without prior indications of Cu insufficiency is not desirable. The particles were effective when given to lambs from birth, but did not increase hepatic Cu concentrations in lambs when ewes were dosed post partum. A dose of 1 g particles/lamb was as effective as a 2 g dose in increasing hepatic Cu concentration, and lambs given 2 g were lighter than those given 1 g; the dose increased hepatic Cu concentrations for at least 292 days. Cu-EDTA was given subcutaneously at the rate of 50 mg Cu for sheep and 150 mg Cu for cattle, and was as effective in increasing hepatic Cu concentration as 45 mg oxidized particle/kg liveweight; it did not produce the severe reactions frequently reported in the literature. The soluble glass pellet was less effective, but studies with a later prototype suggest that subsequent formulations may be more satisfactory.