Niacin supports energy metabolism, skin integrity, digestive tract health, and nervous system function. Horses are efficient at synthesizing niacin from the amino acid tryptophan and also receive niacin from hindgut bacterial production, making dietary deficiency essentially unknown in equines on a normal forage diet.
No specific NRC requirement has been established for horses because deficiency does not occur under normal conditions. Horses synthesize adequate niacin from tryptophan and hindgut bacteria. Dietary sources from hay and grain provide additional niacin at roughly 20 to 40 milligrams per kilogram of feed.
Niacin deficiency has not been documented in horses under normal feeding conditions. Theoretical signs would include skin lesions, digestive upset, and poor appetite, similar to pellagra in humans.
Niacin is water-soluble and excess is excreted readily. Toxicity is not a concern from dietary sources.
| Life Stage | Size | Min | Max | Unit | Notes |
|---|---|---|---|---|---|
| Adult | — | 0 | 0 | mg | No NRC requirement established. Horses synthesize niacin from tryptophan and receive it from hindgut bacteria. Deficiency has not been documented under normal feeding conditions. |
Source: NRC 2007
