EN
Two groups of 7 calves were given oral daily doses of 1000 and 1500 mg of ZnO for 3 months. Complement haemolytic activity, gamma globulin content and serum bactericidal properties were registered four times in control and experimental animals. Blood opsonophagocytic activity and glucose level were also determined. Markedly favourable influence of a 1000-mg dose of ZnO on the phagoopsonic activity and glucose level was observed. No significant effect of the zinc doses on the other immune parametres was demonstrated. Also, no influence of zinc on weight gain in the beef calves was found.