Effect of copper supplementation on copper status of pregnant mares and foals

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