EFFECT OF COPPER AND IRON ON NEUTROPHIL FUNCTION AND HUMORAL IMMUNITYOF GESTATING BEEF-CATTLE

Eighty gestating beef cattle were wed to determine the effect of trace mineral salt mixtures containing copper (Cu) and iron (Fe) on selecte d immune functions and factors affecting copper bioavailability. Pastu red cattle were randomly assigned to receive one of the following comb inations of Cu and Fe in the free-choice trace mineral salt: (1) 0 mg of Cu/0 mg of Fe/hg of trace mineral salt, (2) 1,600 mg of Cu (CuSO4)/ 3,000 mg of Fe/kg of trace mineral salt, (3) 1,600 mg of Cu (CuSO4)/0 mg of Fe/kg of trace mineral salt, and (4) 1,600 mg of Cu (CuCO3)/3,00 0 mg of Fe/kg of trace mineral salt. Total Cu/Fe consumption (from tra ce mineral salt) was 2/678, 193/1,050, 162/553, and 202/1,140 mg/head/ d, respectively, for the 4 groups. After a 1-month period of acclimati on and also on day 28 of the 36-day study, copper concentrations in se rum were significantly (P < 0.05) lower in group 1 than in groups 3 an d 4. Serum copper concentrations did not increase with time for any gr oup, whereas hepatic copper concentrations increased significantly (P < 0.05) with time for all groups except group 1. Hepatic iron concentr ations were similar among groups at the time of the initial and final hepatic biopsies on days 0 and 28, respectively. Hepatic iron concentr ations increased significantly (P < 0.05) with time in groups 3 and 4. Humoral response to chicken gamma-globulin was high but did not diffe r among groups on any of the days analyzed. Neutrophil function tests, consisting of hydrogen peroxide production, phagocytosis of latex par ticles, calcium uptake, and superoxide production, were different only for phagocytosis among groups; the percentage of neutrophils phagocyt osis latex beads was significantly (P < 0.05) lower for group 2 than t he other groups. A similar reduction in phagocytosis was prevented by the omission of additional Fe from the trace mineral salt groups 1 and 3) or we of CuCO3 group 4).