Efficiency of Selection Methods: Increasing Order

Correct Answer: Tandem < Independent Culling < Selection Index

From the notes: Multi-trait selection methods given by Hazel and Lush (1942), in increasing order of efficiency:

1. Tandem Selection (Least Efficient)

• One trait selected at a time
• Does not account for genetic correlations between traits
• Slow overall genetic progress

2. Independent Culling Method

• Minimum culling standard fixed for every trait simultaneously
• An animal failing to meet the standard for ANY ONE trait is culled regardless of merit in others
• Example (from notes): Minimum standard = 10 L milk/day and 5% fat. A cow giving 15 L milk with 4% fat is CULLED.

3. Selection Index (Most Efficient)

• A single numerical expression predicting the breeding value of an individual
• All traits weighted simultaneously using their genetic parameters and economic values
• A scorecard is prepared; animal with highest score is selected
• Best method of selection ✔