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Long-term selection for protein amount over 70 generations in mice
1Institute of Cell, Animal and Population Biology, University of Edinburgh, Scotland. lutz.bunger@ed.ac.uk
Genetical Research
|January 12, 1999
Summary
This study successfully increased mouse carcass protein content by 80% over 70 generations through long-term selection, demonstrating significant genetic gains in protein amount and body weight. The findings highlight the impact of population heterogeneity and selection duration on breeding outcomes.
Area of Science:
- Animal Genetics
- Quantitative Genetics
- Animal Breeding
Background:
- Long-term selection experiments are crucial for understanding genetic responses to breeding goals.
- Previous studies have explored selection for various traits in mice, but sustained selection for carcass protein amount is less documented.
- The Fzt:Du mouse strain, derived from diverse genetic lines, provides a heterogeneous base population for selection studies.
Purpose of the Study:
- To investigate the long-term genetic response to selection for increased total protein amount (PA) in mouse carcasses.
- To analyze changes in heritability, genetic, and phenotypic variance over 70 generations of selection.
- To examine the correlated effects of protein selection on body weight and body composition.
Main Methods:
- A selection experiment initiated in 1975 on the Fzt:Du mouse strain, selecting for carcass protein amount (PA).
- An unselected control line (CO) maintained under identical conditions for comparison.
- Regular measurements of protein amount and body weight at various ages throughout 70 generations.
Main Results:
- Carcass protein amount (P42) in males increased by 97% of the theoretical selection limit, reaching 5.2 g by generation 70.
- Realized heritability for protein amount decreased significantly from 0.56 to 0.03, attributed to increased phenotypic and reduced genetic variance.
- Strong positive phenotypic and genetic correlations between body weight and protein amount were observed, with selection for protein opposing increased fatness.
Conclusions:
- Long-term selection for carcass protein amount is effective, achieving substantial gains and approaching theoretical limits.
- The study demonstrates the complex interplay between genetic and phenotypic variance during prolonged selection.
- The findings have implications for animal breeding strategies, particularly in optimizing growth and body composition through correlated trait selection.