Topics:
Animal Nutrition, Animal Refresher
Optimum Nitrogen to Sulfur Ratio
For optimum use of urea, N:S ratio in diet should be:
- 10:1 — Correct Answer
- 15:1
- 20:1
- None
Explanation:
Correct Answer: 10:1
For optimum utilization of urea (NPN) in ruminant diets, the Nitrogen : Sulphur (N:S) ratio should be 10:1. Sulphur is essential for the synthesis of sulphur-containing amino acids (methionine, cysteine) by rumen microbes, which rely on NH₃ from urea. Without adequate S, NH₃ cannot be efficiently incorporated into microbial protein.
Why N:S Ratio Matters
| Parameter | Recommended Value | Significance |
|---|---|---|
| N : S ratio in ruminant diet | 10:1 | Optimal microbial protein synthesis from NPN |
| N : S ratio in wool | 5:1 | High S content of keratin (wool = 4% S) |
| Starch : Urea ratio | 10:1 | Energy for microbial NH₃ assimilation |
Sulphur-Containing Compounds in Nutrition
- S-containing vitamins: Thiamine (B₁) and Biotin (B₈).
- S-containing amino acids: Methionine, Cysteine, Homocysteine, Taurine.
- S-containing hormones: Insulin, ADH/Vasopressin, Oxytocin.
- Recommended N:S ratio in ruminant diet = 10:1 for optimal urea utilization.
Why Other Options Are Wrong
- 15:1 → too high; insufficient sulphur relative to nitrogen → impaired microbial protein synthesis.
- 20:1 → severely S-deficient; microbial activity would be compromised.
- None → 10:1 is the textbook standard.
📚 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.
