Zinc, copper and iron utilisation by chicks fed various concentrations of zinc

Abstract

1. Zinc, iron and copper interactions were examined in chicks (New Hampshire X Single Comb White Leghorn) grown individually in stainless steel cages and fed on purified diets with three concentrations of zinc: control (37 mg Zn/kg), moderate (100 mg Zn/kg) and excess (2000 mg Zn/kg) in three studies. 2. Chicks given either moderate or excess zinc excreted more than twice as much 65Zn from a test diet as those fed on the control diet. Thus chicks given the moderate amount of zinc had concentrations of zinc in tissues similar to those of controls but chicks given excess zinc accumulated zinc in their tissues. 3. The specific activity of 65Zn in the tissues, especially in the bursa of Fabricius, of chicks given excess zinc was not reduced as much as would be predicted. Thus, ingestion of excess zinc appeared to reduce tissue turnover of 65Zn, especially in the bursa. However, humoral immune responses, as measured by antibody titres to sheep red blood cells, were not affected. 4. Chicks given excess zinc or pair-fed on the control diet retained less 59Fe from a test diet than chicks given control or moderate concentrations of zinc ad libitum. The iron concentrations in tibiae of chicks given excess zinc were depressed.

Pancreatitis in wild zinc-poisoned waterfowl

“…Hepatic Zn increased more than 10-fold in that study, when the dietary concentration was increased to about 2200 mg/kg (Stahl et al, 1989). In mallards, liver concentrations (wet weight) increased from 54 to 401 mg/kg Zn as the dietary concentration increased from control concentrations to 3000 mg/kg (Gasaway & Buss, 1972).…”

“…For example, the whole body concentrations of Zn in songbirds from a site severely contaminated with Zn from smelting were less than 20% greater than those of songbirds from a reference site, although the A1 soil horizon of that contaminated site had more than 10 times the Zn concentration of the reference site (Beyer et al, 1985). In experimental studies on chickens, hepatic Zn concentrations (wet weight) remained constant as the dietary concentration was increased from 37 to about 110 mg/kg (Stahl et al, 1989).…”

“…Geese fed a diet adequate in Cu were reported to have hepatic Cu concentrations of 6.0 to 26 mg/kg wet weight (about 20 to 97 mg/kg dry weight) and renal Cu concentrations 3.0 to 9.0 mg/kg wet weight (about 10 to 30 mg/kg dry weight) (Puls, 1994). Stahl et al (1989) found that exposure to high Zn concentrations in chickens reduced hepatic Cu, and Levengood et al (1999) found that exposure to high Zn concentrations in mallards reduced hepatic Cu concentrations and increased renal Cu concentrations. Both an increase (Levengood et al, 1999) and a decrease (Stahl et al, 1989) in Cu concentrations in the pancreas have been reported in response to exposure to high Zn concentrations.…”

“…Stahl et al (1989) found that exposure to high Zn concentrations in chickens reduced hepatic Cu, and Levengood et al (1999) found that exposure to high Zn concentrations in mallards reduced hepatic Cu concentrations and increased renal Cu concentrations. Both an increase (Levengood et al, 1999) and a decrease (Stahl et al, 1989) in Cu concentrations in the pancreas have been reported in response to exposure to high Zn concentrations. Goose 3 had normal Cu concentrations in the liver and kidney, based on the criteria of Puls (1994).…”

Chelated minerals for poultry

“…Broilers receiving excess inorganic zinc accumulate a higher proportion of zinc in their tissues, and seem to present reduced iron turnover, as well as lower iron and copper concentrations in the liver and pancreas, and lower iron in tibia (Stahl et al, 1989). Patton (1997) suggested that the use of mineral chelates should made after further observations of their actions on animal metabolism.…”