RESUMO
1. Studies on the effect of supplementing copper and cobalt were conducted in 4- to 10-month-old dairy calves during successive indoor and outdoor feeding periods on conserved forages and fresh pastures respectively. 2. No significant differences in live-weight gains or serum Cu were recorded during the indoor period of 40 d. 3. Both live-weight gains and serum Cu were significantly elevated (P < 0.05) by Cu supplementation during the following grazing period of 70 d. 4. Supplementation with Co alone had no effect on any of the measurements taken, but it had an additive effect on weight gains to Cu supplementation during the grazing period. 5. It is concluded that Cu deficiency at marginal level is prevalent in the Mbeya area of Tanzania and that this is due to low Cu and high molybdenum in herbage.
