This is from Prescription for Nutritional Healing:
Vitamin B3 (Niacin, Niacinamide, Nicotonic acid)
Vitamin B3 is needed for proper circulation and healthy skin. It aids in the functioning of the nervous system; in the metabolism of carbohydrates, fats and proteins; and in the production of hydrochloric acid tor the digestive system. It is involved in the normal secretion of bile and stomach fluids, and in the synthesis of sex hormones. Niacin lowers cholestrol and improves circulation. It is helpful for schizophrenia and other mental illnesses, and is also a memory-enhancer. Pellagra is a disease caused by niacin deficiency. Other symtoms of niacin deficiency include canker sores, dementia, depression, diarrhea, dizzyness, fatigue, halitosis, headaches, indegestion, insomnia, limb pains, loss of appetite, low blood sugar, muscular weakness, skin eruptions, and inflammation.
Niacin and niacinamide are found in beef liver, brewer's yeast, broccoli, carrots, cheese, corn flour, dandelion greens, dates, eggs, fish, milk, peanuts, pork, potatoes, tomatoes, wheat germ, and whole wheat products, Herbs that contain niacin include alfalfa, burdock root, catnip, cayenne, chamomile, chickweed, eyebright, fennel seed, hops, licorice, mullein, nettle, oatstraw, parsley, peppermint, raspberry leaf, red clover, rose hips, slippery elm, and yellow dock.
Of course this information is all geared for people, but clearly some of it will also apply toward waterfowl.
Hmmmmm . . . . Ever see a flock of schizophrenic ducks?