Implications of non-linear economic weights for breeding

Area of Science:

• Quantitative genetics
• Animal breeding
• Agricultural economics

Background:

• Selection candidates (parents) can be individuals, crosses, or clones.
• Offspring production can be sexual or vegetative.
• Economic worth (profit) functions for offspring can be linear or non-linear.

Purpose of the Study:

• To theoretically investigate the relationship between parental phenotypic values and offspring economic worth.
• To evaluate the impact of different population structures, profit functions, and heritabilities on selection efficiency.

Main Methods:

• Theoretical modeling of selection scenarios.
• Analysis of three offspring generation systems: clonal propagation, pair (full-sib) crosses, and half-sib crosses.
• Inclusion of linear, intermediate optimum, and acceptable versus cull profit functions.
• Independent variation of heritabilities for parents and offspring.

Main Results:

• Low heritabilities and genetic segregation reduce the impact of non-linear economic worth functions.
• Linear weightings in selection indices are generally adequate for monotonic profit functions.
• Corrective mating benefits are minimal with low heritabilities and individual offspring profit functions.
• Genetic uniformity (clones) with non-linear profit functions requires high offspring heritability for economic gain.

Conclusions:

• Selection index linearity is often a good approximation, simplifying breeding program design.
• High heritability, particularly in offspring, is crucial for realizing economic benefits from genetic uniformity and non-linear profit functions.
• The interplay between heritability, genetic structure, and profit function dictates optimal breeding strategies.