Topics:
Animal Nutrition, Animal Refresher
Safe Inclusion Level of NPN
NPN feed-ingredient is added to ruminant diet at what % of concentrate mixture?
- 3% — Correct Answer
- 1%
- 5%
- 4%
Explanation:
Correct Answer: 3%
The safe maximum inclusion level of NPN (Non-Protein Nitrogen) — primarily urea — in ruminant concentrate mixture is 3%. Exceeding this threshold risks ammonia toxicity when rumen NH₃ concentration surpasses 80 mg/100 ml.
NPN/Urea Inclusion Guidelines in Ruminant Rations
| Feed Type | Urea Inclusion Level |
|---|---|
| Dry roughage (straw) | 4% of straw dry weight |
| Succulent roughage (silage) | 0.5% of wet material |
| Concentrate mixture | Up to 3% of total concentrate |
| Total ration (DM basis) | Up to 1% of total DM |
Urea Toxicity — Key Facts
- Urea toxicity occurs when rumen NH₃ > 80 mg/100 ml or blood NH₃ > 1 mg/100 ml.
- Treatment: 20–40 litres cold water drench OR 4–5 litres 10% acetic acid.
- Urea must NEVER be fed to young calves (<6 months) or monogastric animals.
- Nitrogen content of pure urea = 46.6%.
Why Other Options Are Wrong
- 1% → this is the inclusion level in the total DM of the ration, not in concentrate alone.
- 5% → exceeds safe limits; risks acute urea/ammonia toxicity.
- 4% → used for straw treatment (100 kg straw + 40 L water + 4 kg urea), not concentrate.
📚 About this Topic — Animal Nutrition
This multiple choice question is from Animal Nutrition, Animal Refresher. It has 4 options with a detailed explanation of the correct answer. Practice more MCQs from Animal Nutrition to strengthen your preparation.
