EFFECTS OF MONOTYPIC DIETS OF SOYBEAN, RICE, AND CORN ON MALLARD (ANAS-PLATYRHYNCHOS) PHYSIOLOGICAL STATUS

The effects of monotypic diets of agricultural grains on mallard (Anas platyrhynchos) physiological status were tested. Restricted amounts o f six diets were fed to captive hen mallards housed in an outdoor avia ry at the White River National Wildlife Refuge (Arkansas County, Arkan sas, USA). Dietary treatment groups included 1) a 23% protein (high pr otein) control, 2) a 7% protein (low protein) control, 3) corn, 4) ric e, 5) soybeans, and 6) a natural diet, consisting of equal amounts of willow oak acorns (Quercus phellos), Pennsylvania smartweed (Polygonum pennsylvanicum), and Japanese millet (Echinocloa crusgalli) by weight . These diets represent foods available to wild mallards in the Missis sippi alluvial valley during winter. Effects of diet on mallard physio logical status were determined by measuring body weight at 8 wk and se rum metabolites and gamma globulins at 9 wk. No diets induced protein deficiency, as indicated by final equivalent serum total protein and g amma globulin levels among groups fed different diets. The soybean die t, however, caused a negative energy balance as shown by higher serum D-beta-hydroxybutyrate levels.