Effect of copper supplementation on the copper status of pasture‐fed young Thoroughbreds

Abstract

Summary The effect of copper supplementation of pasture fed mares and foals on the copper status of the foals, in terms of plasma, soft tissue and bone copper concentrations and caeruloplasmin activity, was investigated. Twenty‐one Thoroughbred foals from either control mares (n = 9), or copper‐supplemented mares (n = 12) were divided randomly into control (pasture only, n = 10) or supplemented (pasture and oral copper sulphate, n = 11) groups. The pasture diet was grazed by all animals, and contained 4.4–8.6 mg Cu/kg dry matter (DM). The copper supplement for the mares contained copper sulphate equivalent to 0.5 mg Cu/kg liveweight (LW)/day. This daily dose was converted to allow administration as a thrice weekly dose (i.e. multiplied by 7/3) which was given for 13–25 weeks prior to foaling. The supplemented foals, also dosed 3 times a week, received 0.2 mg Cu/kg LW/day at age 21 days, which was increased to 0.5 mg Cu/kg LW/day at 49 days and was continued at this level until euthanasia at 150 days. Foal plasma copper concentration and caeruloplasmin activity increased from birth to 21 days post partum and then plateaued at a concentration similar to the mare, but the rise in these indices was not affected by copper supplementation of the mare or foal. Copper supplementation of the foal increased foal liver copper concentration at 150 days (P<0.03). Copper intake of diets containing approximately 8–28 mg Cu/kg DM is well reflected by liver copper concentration, but is poorly reflected by bone, other soft tissue copper concentrations and circulating copper status indices.

Liver copper kinetics in Thoroughbred foals at pasture from birth to 160 days of age

“…In the current study, plasma Cu increased rapidly from very low levels at birth to levels similar to adults by approximately 30 days of age, as reported by others (Bell et al 1987;Pearce et al 1998b). In an experiment to induce Cu deficiency, foals were fed New Zealand Journal of Agricultural Research, 2004, Vol.…”

“…In the current study there were no significant differences in foal liver Cu concentration between years, or with dam Cu supplementation, indicating that two different regimens of injectable Cu supplementation of dams had no effect on foal liver Cu storage in the first 5 months of life. Conversely, oral Cu supplementation of mares in the last 15-25 weeks of gestation increased the liver Cu concentration of foals at birth, but this effect was not apparent at 5 months of age (Pearce et al 1998b). …”

Developmental orthopedic disease

“…A decrease in the prevalence and severity of OC has been reported in association with oral Cu supplementation of mares during gestation (Cu sulfate as a thrice weekly dose, equivalent daily dose 0.5 mg Cu/kg BW, ~25-30 mg/kg DM, Pearce et al 1998b). In addition, mare copper supplementation decreased radiographic indices of physitis in the distal third metatarsal bone of the foals at 150 days.…”

Abnormalities of the erythron

“…Normal serum copper concentrations in healthy horses probably vary between 0.5 and 1.5 mg/L (8-24 µmol/L). 77,81,82 Normal copper concentrations in liver tissue vary between 3.2 and 11 mg/kg (51-176 µmol/kg) fresh weight. 80 Serum copper concentrations lower than 0.7 mg/L (11.5 µmol/L) can indicate copper deficiency.…”

“…77,81,82 Normal copper concentrations in liver tissue vary between 3.2 and 11 mg/kg (51-176 µmol/kg) fresh weight. 76,82,85 Complete blood count and plasma fibrinogen concentration should therefore be assessed together with serum copper concentrations to detect falsely elevated values. ), 78 and serum ceruloplasmin concentration in adult horses varies between 4.07 ± 0.41 and 6.06 ± 0.74 mg/mL.…”