Best Aid to Selection for Sex-Limited Traits

The most effective aid to selection for improving a sex-limited trait is:

Correct Answer: Progeny Testing

From the notes: Progeny testing is the most effective aid to selection for improving sex-limited traits (e.g., milk production, egg production).

Why Progeny Testing for Sex-Limited Traits

Since sires cannot express sex-limited traits (a bull cannot produce milk), their genetic merit can only be assessed from the performance of their daughters. A sire's breeding value for milk yield = twice the mean deviation of his daughters from the population mean.

Key Facts About Progeny Testing (from notes)

• Used for selection of SIRE
• Sire = half of the herd
• Most effective and best basis of selection
• A 'two-way selection system'
• Increases generation interval → reduces genetic gain per year
• In ONBS: sibling test is preferred over progeny testing (shorter generation interval despite being less accurate)

BLUP (from notes)

The most recent and best method of sire evaluation = BLUP (Best Linear Unbiased Prediction).