Related Experiment Videos
Response to long-term selection for egg production in laying hens
D G Poggenpoel1, G F Ferreira, J P Hayes
1Department of Animal Sciences, University of Stellenbosch, Matieland, South Africa.
British Poultry Science
|September 1, 1996
Summary
This study tracked genetic changes in White Leghorn hens over 28 years. Initial selection for egg number significantly impacted traits, while later focus on egg weight showed trade-offs.
Area of Science:
- Animal Science
- Genetics
- Poultry Breeding
Background:
- Long-term selection experiments are crucial for understanding genetic trait evolution in livestock.
- White Leghorn chickens have been historically important for egg production.
Purpose of the Study:
- To estimate genetic changes in egg production and related traits in a White Leghorn line over a 28-year selection period.
- To analyze the impact of differing selection pressures on egg number and egg weight.
Main Methods:
- Selection of a White Leghorn line for hen-housed egg production from 1962 to 1990.
- Estimation of genetic changes as deviations from an unselected control line.
- Analysis of trait changes under different selection phases: primarily egg number, then increased egg weight pressure.
Main Results:
- Early selection for egg number (to 273 days) significantly improved production but decreased egg weight and body weight.
- Later selection incorporating egg weight pressure led to positive changes in egg weight with minimal negative impact on egg number.
- Heritabilities for egg production and egg size remained relatively stable, but the realized genetic correlation between egg number and egg weight was strongly negative (-0.97).
Conclusions:
- Long-term genetic selection can effectively alter complex traits in poultry populations.
- Balancing selection for multiple traits, like egg number and egg weight, is essential to avoid undesirable correlated responses.
- Understanding genetic correlations is vital for optimizing breeding strategies in commercial poultry.