EFFECT OF CADMIUM ON PEKIN DUCK TOTAL BODY WATER, WATER FLUX, RENAL FILTRATION, AND SALT GLAND FUNCTION

Abstract

The following hypotheses were examined using Pekin ducks (Anas platyrhynchos) as a model for marine ducks: cadmium (Cd) intake affects (1) salt gland and/or kidney function of ducks and (2) osmoregulation differently in male and female ducks. Birds were fed 0, 50, or 300 mug Cd/g food. They were gradually acclimated to 450 m M NaCl and then drank 300 m M NaCl for 3 mo while salt gland secretion (SGS), glomerular filtration rate (GFR), total body water (TBW), and water flux (WF) were measured in ducks eating control and high-Cd diets. Cadmium ingestion did not markedly affect body mass, but significantly enlarged the salt glands and kidneys. Enhancement of kidney mass was greater in males. Cadmium ingestion did not affect TBW or WF, but tended to increase interstitial fluid space at the expense of intracellular fluid. Sex did not affect TBW, but males had greater WF. Birds that ate Cd diets, especially the higher Cd diet, exhibited renal tubular damage and lower GFR. Ducks that ate Cd had lower plasma sodium concentration and osmolality and, to activate SGS, required longer infusion of NaCl and larger increments in extracellular osmolality and volume. Cadmium ingestion did not affect SGS rate or [Na+]. Both hypotheses were accepted since birds that ate Cd had lower GFR and delayed onset of SGS in response to salt challenge and the effects of Cd on the size and response of excretory organs were sexually disparate. Cadmium appeared to compromise the salt excretion of Pekin ducks. However, they are less salt tolerant than seaducks and, in this study, had higher organ Cd concentrations than those seen in wild ducks. Further studies are needed to determine if these observations also apply to the more salt-tolerant seaducks.