Niacin is a water-soluble B vitamin, which is also known as vitamin B3 or nicotinic acid.
Nicotinamide is the derivative of niacin and used by the body to form the coenzymes nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP). Nicotinic acid and nicotinamide are rapidly absorbed from the stomach and the intestine. Ducks have a very high niacin requirement, approximately twice as high as chickens and humans. The increased requirement is related to the ducks inability to synthesize niacin from tryptophan efficiency, resulting from the presence of high amounts of enzyme, picolinic acid carboxylase in the liver.
Table 1: Picolinic Acid Carboxylase Activity in Different Species
|Species||Units/g Liver (wet basis)|
|Table Adapted from Scott et al. (1982)|
Causes of Niacin Deficiency
Niacin deficiency in ducks may result from inadequate dietary intake of niacin and/or tryptophan. Other nutrient deficiencies may also contribute to the development of niacin deficiency. When ducklings hatch they have considerable tryptophan contained in the protein of the yolk, if it is fully absorbed. Ducklings are at risk of niacin deficiency if the starter feed contains low levels of the amino acid, tryptophan or niacin. Most corn-based duck feeds provide limited levels of tryptophan.
What are the Clinical Signs of Niacin Deficiency?
Ducks receiving low-niacin diets show severely bowed legs and/or enlarged hock joints and ultimately become so crippled and weak that they cannot walk. Niacin deficiency in adult ducks presents as severe metabolic disorders in the skin and digestive organs.
Dietary Sources of Niacin
Niacin is widely distributed in feedstuffs of both plant and animal origin. The best food sources of niacin include distiller’s grains, Brewer's yeast, beets, fish, various distillation and fermentation solubles, sunflower seeds, and certain oilseed meals. The availability of niacin in grain and grain by-products is very low. Other sources of niacin include tablets or capsules in both regular and timed-release forms.
Recommended Dietary Allowance of Niacin in Ducks
Requirements for niacin in ducks at various stages of life are:
Table 2: Duck Niacin Requirements
|Age Range||Niacin (mg)|
|0 to 7 weeks||70|
|Older than 7 weeks||50|
Niacin is commercially available in two forms, niacinamide and nicotinic acid, with both forms providing about the same niacin biological activity.