Topics:
Animal Nutrition, Animal Refresher
Ruminal Degradability of Urea
Maximum degradability of urea in rumen is:
- 100% — Correct Answer
- 80%
- 60%
- 0%
Explanation:
Correct Answer: 100%
Urea is 100% rumen-degradable. Unlike natural proteins which have varying degradability (rumen degradable protein vs bypass protein), urea is hydrolyzed almost instantaneously by ruminal urease enzyme into NH₃ and CO₂. There is no bypass fraction for urea.
Rumen Degradability of Common Protein Sources
| Protein Source | Rumen Degradability (%) |
|---|---|
| Urea | 100% (no bypass) |
| Casein | ~90–95% (highly degradable) |
| Soybean meal | ~65–70% |
| Maize (corn) | ~40–50% |
| Feather meal | ~20–30% (high bypass) |
| Blood meal | ~20% (high bypass) |
Implications of 100% Degradability
- Urea must be fed with sufficient rapidly fermentable carbohydrate (starch) for microbial NH₃ utilization.
- Starch:Urea ratio of 10:1 (1 kg starch per 100 g urea) is optimal.
- Rate of NH₃ release exceeds microbial utilization if overfed → ammonia toxicity.
Why Other Options Are Wrong
- 80% → applies to some high-protein meals; urea has no escape fraction.
- 60% → typical for average feed proteins; not applicable to urea.
- 0% → zero would mean no degradation; opposite of reality for urea.
📚 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.
