Influence of dietary calcium on lead poisoning in mallard ducks (Anas platyrynchos)

Abstract

SUMMARY Forty-five mallard ducks were allotted into 3 dietary groups. Group I was fed pelleted calcium-supplemented corn; group II was fed a pelleted commercial duck ration; and group III was fed cracked corn. Ten ducks of each group were given four No. 4 lead shot via an esophageal tube, and 5 ducks of each dietary group were kept as pair-fed controls. Anorexia and weight loss were most severe in the treated group III ducks. Group III had a maximum reduction in food consumption of 87% followed by a slight improvement in appetite; they lost 35% of their initial body weight. Group I treated ducks had a reduction in food consumption of 64% that eventually returned to the quantities consumed at the start of the experiment; group I ducks lost 18% of their initial body weight. Group II treated ducks maintained healthy appetites during the experiment and had a weight gain of 2% of their initial body weight. The number of ducks that became moribund and were euthanatized differed significantly among the treated groups with 100% of group III, 50% of group I, and 0% of group II treated ducks becoming moribund. All 3 groups of treated ducks had increased protoporphyrin IX concentrations compared with controls. Groups I and III lead-treated ducks had significant (P < 0.05) reductions in erythrocyte counts, pcv , hemoglobin concentrations, and mean corpuscular hemoglobin concentrations as compared with controls. Group II had reduced hemoglobin concentration and mean corpuscular hemoglobin concentration compared with controls. However, none of the above changes differed statistically among the 3 dietary groups of lead-poisoned ducks. Gross pathologic lesions of treated ducks (pectoral muscle atrophy and green discoloration of the gizzard mucosa) were most pronounced in group III, followed by group I and group II, in that order. Histopathologic lesions consisting of neuropile vacuolization, intranuclear inclusion bodies, neuronal degeneration, and myocardial and pectoral muscle degeneration, necrosis, and atrophy occurred most frequently in the group III treated ducks, less in the group I treated ducks, and least in the group II treated ducks. This suggested that, whereas the addition of calcium to the corn diet had an ameliorating effect, other nutrients were also important in mollifying lead absorption and metabolism in mallard ducks.