ACUTE EFFECTS OF LEAD, STEEL, TUNGSTEN-IRON, AND TUNGSTEN-POLYMER SHOT ADMINISTERED TO GAME-FARM MALLARDS

Sixteen-bird groups (sexes equal) of adult mallards (Anas platyrhyncho s) were orally dosed with eight #4 steel shot, eight #4 lead shot, eig ht BE-size tungsten-iron shot, eight BB-size tungsten-polymer shot, or were sham-dosed and maintained for 30 days (16 January 1996 to 15 Feb ruary 1996). Half of the lead-dosed ducks (five males, three females) died during the study, whereas no ducks died in the other dosage group s. For lead-dosed ducks, hematocrit and hemoglobin concentration were decreased on day 15 of the trial, but not on day 30. Delta aminolevuli nic acid dehydratase activity in lead-dosed ducks was lower when compa red to steel-dosed ducks only. Plasma activities of selected enzymes w ere elevated in lead-dosed ducks when compared to enzyme activities of ducks in the other groups. For lead-dosed ducks, relative heart, live r, and kidney weights increased in comparison to relative weights of t hose organs of ducks in other groups. Histology of tissues indicated t hat renal nephrosis accompanied by biliary stasis was present in the e ight lead-dosed ducks that died. For the eight lead-dosed ducks that s urvived, six had mild to severe biliary stasis. Mild biliary stasis wa s noted in five tungsten-iron dosed ducks and three tungsten-polymer d osed ducks. Amounts of lead in the femur, liver, and kidneys were high er in lead-dosed ducks than in ducks of the other four groups. Small a mounts of tungsten were detected in the femur and kidneys of two tungs ten-polymer dosed ducks. Higher concentrations of tungsten were detect ed in the femur, liver, and kidneys of all tungsten-iron dosed ducks. The rate of shot erosion was highest (80%) for the tungsten-polymer sh ot, followed by tungsten-iron (55%), lead (50%), and steel shot (33%). Results indicated that tungsten-iron or tungsten-polymer shot (8 shot /duck) orally administered to mallards did not adversely affect them d uring a 30-day trial.