Dietary vitamin intake and utilization are influenced by a host of factors. These factors combine to increase the vitamin levels needed to maintain optimum productivity. They include:
Direct factors: stressors on the animal
- Disease
- Confinement
- Restricted feeding
- Antagonists
- Air quality
- Temperature
Indirect factors: variations in vitamin levels in feedstuffs
- Bioavailability
- Stability
- Quality of feedstuffs