Genetic Gain Per Year: Key Factor

Correct Answer: Generation Interval

From the notes: Genetic gain per year = Response to selection (R) / Generation interval (L). The generation interval is the average age of parents when their offspring are born.

Implications

• Progeny testing increases generation interval (sire must wait for daughters to complete lactation) → reduces genetic gain per year, despite being the most accurate method
• In ONBS: Sibling test is preferred over progeny testing because shorter generation interval → higher genetic gain per year (even though less accurate)
• MOET (Multiple Ovulation and Embryo Transfer) reduces generation interval → increases genetic gain per year. Used in ONBS for faster genetic improvement.

Formula

Genetic gain/year = (i × h × σA) / L, where i = selection intensity, h = square root of heritability, σA = additive genetic SD, L = generation interval.