Serum and liver zinc, copper, and iron in chicks infected with Eimeria acervulina or Eimeria tenella

Abstract

Two-wk-old broiler chicks were inoculated via crop intubation with Eimeria acervulina at two doses: 10(5) or 10(6) sporulated oocysts/bird or with Eimeria tenella at a dose of 10(5) sporulated oocysts/bird. Serum and liver samples were collected on days 3 and 6 post-inoculation (PI). There were no significant changes in serum or liver zinc, copper, and iron concentrations in any of the infected groups by 3 d PI. However, on d 6, PI serum protein was significantly reduced in all of the infected groups compared to their pair-fed controls. The chicks infected with E. tenella had significantly reduced serum zinc (1.20 vs 1.77 micrograms/mL) and iron (0.44 vs 1.28 micrograms/mL) concentrations and significantly elevated serum copper (0.28 vs 0.17 micrograms/mL) and ceruloplasmin levels (20.33 vs 11.11 micrograms/mL) compared to their pair-fed counterparts. Those chicks infected with E. acervulina (10(6) oocysts/bird) exhibited significantly reduced serum iron concentration by 6 days PI (0.90 vs 1.14 micrograms/mL). Liver zinc was significantly increased in the chicks infected with E. tenella (349 vs 113 micrograms/g dry liver wt), as was copper (24 vs 19 micrograms/g), whereas liver iron concentration was significantly reduced (172 vs 243 micrograms/g) compared to pair-fed controls. At both dose levels, the chicks infected with E. acervulina exhibited a significant reduction in liver iron by 6 d PI. Hepatic cytosol metals generally reflected whole tissue levels. Metallothionein (MT)-bound zinc was significantly elevated in the chicks infected with E. tenella. Iron bound to a high molecular weight, heat-stable protein fraction (presumably cytoplasmic ferritin) was significantly reduced in chicks infected with E. acervulina, as well as those infected with E. tenella. Collectively, the changes in serum zinc, copper, and iron concentrations, as well as the changes in hepatic zinc and MT-zinc concentrations in the chicks infected with E. tenella were similar to changes evoked during an acute phase response to infection. It is possible that a secondary bacterial infection or inflammation stemming from erosion of the lining of the cecum may play a role in the response of trace element metabolism to the E. tenella infection.