EFFECT OF COPPER SUPPLEMENTATION ON COPPER STATUS OF PREGNANT MARES AND FOALS

Pregnant Thoroughbred mares (n = 21) mere grazed on tall fescue pastur e containing 4.4-8.6 mg Cu/kg dry matter (DM). Twelve mares mere suppl emented with approximately 0.5 mg Cu/kg liveweight (LW)/day as copper sulphate for the final 13-25 weeks gestation. Plasma copper concentrat ion declined during the third trimester for all mares and was not affe cted by copper supplementation. Liver copper concentration of mares an d foals was determined when the foals were 4-10-days-old. Copper suppl ementation of the mares tended to increase mare liver copper concentra tion (P<0.08) and increased foal liver copper concentration (P<0.01). There was a significant relationship between mare and foal lifer coppe r concentration (P<0.001, r(2) = 0.7). Increasing the copper intake of mares is effective in enhancing the copper status of foals.