Topics:
Animal Refresher, Poultry Science
Precursor of Niacin
The precursor of Niacin (Vitamin B₃) is:
- Tryptophan — Correct Answer
- Tyrosine
- Phenylalanine
- Methionine
Explanation:
Correct Answer: Tryptophan
Tryptophan is the metabolic precursor of Niacin (Vitamin B₃). In poultry and mammals, 60 mg of Tryptophan is required to synthesize 1 mg of Niacin. This conversion is, however, very inefficient.
Why This Matters in Poultry Nutrition
- Poultry do not synthesize Niacin adequately from Tryptophan at practical dietary levels, so Niacin must be supplemented in the feed.
- Interestingly, poultry do not require Niacin supplementation from gut bacteria (unlike ruminants), because poultry gut microbiome is limited.
- Poultry do not require Vitamin C in the feed (can synthesize it), unlike guinea pigs and primates.
Key Vitamin Precursor Relationships
- Tryptophan → Niacin (Vit. B₃) ✔
- β-Carotene → Vitamin A
- 7-Dehydrocholesterol → Vitamin D₃ (by UV light)
Why Other Options Are Wrong
- Tyrosine → precursor of thyroid hormones, melanin, and catecholamines; not Niacin.
- Phenylalanine → precursor of Tyrosine; not directly linked to Niacin.
- Methionine → sulphur-containing amino acid; no direct link to Niacin synthesis.
📚 About this Topic — Animal Refresher
This multiple choice question is from Animal Refresher, Poultry Science. It has 4 options with a detailed explanation of the correct answer. Practice more MCQs from Animal Refresher to strengthen your preparation.
