Long term selection for four-week body weight in Japanese quail under different nutritional environments

Area of Science:

• Animal Genetics
• Quantitative Genetics
• Animal Breeding

Background:

• Phenotypic selection is a key driver of genetic gain in livestock.
• Environmental factors significantly influence the effectiveness of selection programs.
• Understanding genotype-environment interactions is crucial for optimizing breeding strategies.

Purpose of the Study:

• To investigate the long-term effects of phenotypic selection for 4-week body weight in Japanese quail.
• To evaluate the impact of different protein environments on selection response.
• To explore the efficacy of changing selection environments to enhance genetic gains.

Main Methods:

• Individual phenotypic selection for 4-week body weight over 40 generations in Japanese quail.
• Two selection lines (P and T) were maintained under distinct dietary protein levels (28% and 20% with thiouracil).
• Sublines (R and S) were created by altering the protein environment during selection to assess plasticity.

Main Results:

• The P line exhibited continuous improvement in body weight, reaching approximately 200g.
• The T line's body weight response plateaued after generation 22.
• Altering the selection environment in sublines R and S resulted in greater body weight gains than the original T line.
• Realized heritability estimates were higher in the P line and decreased over generations in both lines.

Conclusions:

• Sustained selection for body weight can be achieved under an adequate protein environment.
• Environmental plasticity exists, and modifying the selection environment can overcome selection plateaus.
• Changing protein environments following long-term selection is a viable strategy to maximize body weight gains in quail.