Diets Ducks

Water birds have not been shown to be directly affected by acidification. However, the prey of waterbirds may be of concern as these lower food-chain organisms may have elevated levels of toxic metals related to acidification of their habitat. Moreover, most water birds rely on some component of the aquatic food-chain for their high protein diet. Invertebrates that normally supply caJcium to egg-laying birds or their growing chicks are among the first to disappear as lakes acidify. As these food sources are reduced or eliminated due to acidification, bird habitat is reduced and reproductive rate of the birds is affected. The Common Loon is able to raise fewer chicks, or none at all, on acidic lakes where fish populations are reduced 37 and 5S). However, in some isolated cases, food supplies can be increased when competitive species are eliminated (e.g.. Common Goldeneye ducks can better exploit insects as food when competition from fish is eliminated). The collective influences of acidification are difficult to quantify on a specific area basis but for species that rely on a healthy aquatic ecosystem to breed, acidification remains a continuing threat in thousands of lakes across eastern North America 14). 

Birds are comparatively resistant to the biocidal properties of cadmium. Adult drake mallards (Anas platyrhynchos) fed up to 200 mg cadmium per kg diet for 90 days all survived with no loss of body weight (White and Linley 1978). Laying hens fed 200 mg Cd/kg diet also survived egg production was suppressed at that concentration but not at lower concentrations (White and Linley 1978). Marine and terrestrial animals, including ducks, have been shown to be particularly abundant in a wildlife community associated with a marine sewer outfall (Brown et al. 1977). These animals were contaminated with high levels of cadmium, as well as zinc and copper, but were apparently protected from the deleterious effects of high metal body burdens by metallothioneins. Amounts... 

The effect of diet on vulnerability to lead makes interpretation of published information on experimental lead poisoning in waterfowl extremely difficult (Chasko et al. 1984). For example, many mallards on a diet of com die within 10 to 14 days after ingesting a single lead shot, whereas similar birds on a balanced commercial duck ration appear outwardly normal after ingesting as many as 32 pellets of the same size (Wobeser 1981). Also, multiple nutritional deficiencies may have additional effects in potentiating the toxicity of lead in mallards (Carlson and Nielsen 1985). Under conditions of reduced dietary calcium availability, such as can occur in acid-impacted environments, birds risk increased uptake of lead (and other metals) and may accumulate toxic concentrations more rapidly (Scheuhammer 1996). Enhanced accumulation of lead was accompanied by an increased synthesis of metallothioneins and a greater inhibition of ALAD activity (Scheuhammer 1996). 

Females fed diets for 12 weeks containing 80 mg Pb/kg ration (as lead acetate) alone or in combination with 8 mg Hg/kg (as methylmercury chloride), or 80 mg Cd/kg ration (as cadmium chloride), ora mixture of Pb, Hg, and Cd Renal corpuscles of ducks fed Pb, Fig, or Cd alone or in two-way combinations had minor ultrastructural changes when compared to controls. The diet containing all three metals caused marked ultrastructural changes in kidney 40... 

Adult males, age 16 weeks, fed pelleted commercial duck diet for 10 weeks diet formulated to contain 24% lead-contaminated sediment (3400 mg Pb/kg DW sediment = 816 mg Pb/kg DW total diet) 1 of 10 died vs. none in controls survivors had atrophied breast muscles, green staining of feathers around the vent, viscous bile green staining of the gizzard lining, and renal intranuclear inclusion bodies. Blood had 6.1 mg Pb/kg FW, liver had 2.8 mg Pb/kg FW, and feces had 1660 mg Pb/kg DW 61... 

As above, except mallards were fed a nutritionally balanced commercial duck diet containing 24% lead-contaminated sediments (4000 mg Pb/kg DW sediment) No deaths livers had 13 mg Pb/kg DW 61... 

At 3000 mg/kg ration, ducks had leg paralysis and decreased food consumption at >3000 mg/kg diet, many deaths occurred (NAS 1979). 

Phenylarsonic feed additives for disease control and improvement of weight gain in domestic poultry safe dietary levels Maximum levels in diets, in mg/kg feed, are 50-100 for arsanilic acid, 25-188 for 3-nitro-4-hydroxy-phenylarsonic acid (for chickens and turkeys, not recommended for ducks and geese), and 180-370 for others (NAS 1977)... 

Acute oral LD50 for rats 283 mg/kg, chickens 220 mg/kg, hamsters 1,720 mg/kg, mice 145 mg/kg, rabbits 100 mg/kg (quoted, RTECS, 1985), bobwhite quail 83 mg/kg diet, mallard ducks 795 mg/kg diet (Worthing and Hance, 1991). 

LC50 (8-d) for mallard ducks 1,466 mg/kg diet, Japanese quail 820 mg/kg diet (Worthing and Hance, 1991). 

Now think abont the French. By the standards of American nntritional orthodoxy the diet of the French leaves a good deal to be desired. The French consume butter, cream sauces, sausages, duck confit, foie gras, brie, camembert and 300-plus other cheeses, and rich pastries pretty mnch as they please. In fact, the French consume considerably more satnrated animal fat than do Americans but they live just as long. Beyond that, they wash it down with wine. They seem to do so without worrying much about it at all they view food as a genuine source of pleasure. The French obsess less abont food than Americans they enjoy it more. 

Several excellent accounts have described the need which arose in World War II for new antimalarial drugs, and the chemical reasoning which led to the synthesis of Paludrine (l-p-chlorophenyl-5-isopropylbiguanide) (742, 746, 545). Curd, Davey and Rose (142) found that both Paludrine and its 5-methyl-homologue showed antimalarial activity in chicks and birds chnical trials demonstrated their activity in man. Paludrine presently proved (2) to be of considerable therapeutic value in the prevention and cure of acute human malaria (475). Animal experiments (ducks) indicated (178, 421) that Paludrine was most effectively administered in the diet in order to maintain a suitable concentration in the blood. 

Sharp-shinned hawk, Accipiter striatus eastern United States 1991-93 liver Wood duck, Aix sponsa Northern Idaho lead-contaminated area vs. reference site maximum values Blood Diet Liver... 

Adult males, age 16 weeks, fed pelleted commercial duck diet for 10 weeks diet formulated to contain 24% lead-contaminated sediment (3400 mg Pb/kg DW sediment = 816 mg Pb/kg DW total diet)... 

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