• horse;
  • copper;
  • Thoroughbred;
  • pregnancy;
  • pasture;
  • liver


Pregnant Thoroughbred mares (n = 21) were grazed on tall fescue pasture containing 4.4–8.6 mg Cu/kg dry matter (DM). Twelve mares were supplemented with approximately 0.5 mg Cu/kg liveweight (LW)/day as copper sulphate for the final 13–25 weeks gestation. Plasma copper concentration declined during the third trimester for all mares and was not affected by copper supplementation. Liver copper concentration of mares and foals was determined when the foals were 4–10-days-old. Copper supplementation of the mares tended to increase mare liver copper concentration (P<0.08) and increased foal liver copper concentration (P<0.01). There was a significant relationship between mare and foal liver copper concentration (P<0.001, r2= 0.7). Increasing the copper intake of mares is effective in enhancing the copper status of foals.