Maintaining Hybrid Vigour in Cattle
Maintenance of hybrid vigour in a cattle herd is done by-
- Grading up
- Inbreeding
- Top crossing
- Rotational crossing — Correct Answer
Explanation:
Correct Answer: Rotational crossing
Rotational crossing (using sires from different breeds alternately each generation) effectively maintains a high level of hybrid vigour (heterosis) generation after generation without constant purchase of purebred replacements.
How Rotational Crossing Works
- In a 2-way rotational cross (Criss-cross): Breed A sires used in Gen 1, Breed B sires in Gen 2, back to Breed A in Gen 3…
- The minimum no. of breeds for rotational crossing is two.
- Heterosis stabilizes at a predictable level: 2-breed rotation maintains ~67% of F1 heterosis; 3-breed maintains ~86%.
Heterosis by Mating System
| Mating System | % Heterosis Retained |
|---|---|
| F1 Cross (first generation) | 100% |
| F2 (inter-se) | 50% |
| 2-breed rotational cross | ~67% |
| 3-breed rotational cross | ~86% |
📚 About this Topic — Animal Genetics & Breeding
This multiple choice question is from Animal Genetics & Breeding, Animal Refresher. It has 4 options with a detailed explanation of the correct answer. Practice more MCQs from Animal Genetics & Breeding to strengthen your preparation.
