Some problems in assessing the physiological and economic significance of hypocupraemia in beef suckler herds.

Factors influencing the incidence of hypocupraemia and responses to copper therapy were investigated in three beef suckler herds calving in spring and early summer. On farm A hypocupraemia was most severe (plasma copper less than 0.4 mg per litre) in March for the cows and in October/November for their calves. On farm B plasma copper levels were 30 per cent lower in five to eight-year-old cows than in two-year-old cows in late November. Administration of copper (100 mg) in late pregnancy significantly increased plasma copper in the suckled calves on farm A but not in their dams after parturition. Growth of the calves was not increased. The alleviation of severe hypocupraemia on a third farm (C) by injecting the calf with copper did not improve growth rate. It is concluded that in some areas a severe seasonal hypocupraemia may be tolerated without loss of productivity.