Economic modeling and selection for longevity traits in dairy cattle

Area of Science:

• Animal Breeding and Genetics
• Agricultural Economics
• Dairy Science

Background:

• Estimating the economic significance of cattle longevity traits is complex due to varied definitions and modeling approaches.
• Existing methods like simple profit functions lack biological complexity, while bioeconomic models can be difficult to implement.

Purpose of the Study:

• To develop a versatile framework for estimating the economic value (EV) of diverse longevity traits in cattle.
• To design optimal selection indices that incorporate longevity for improved genetic gain across different production systems.

Main Methods:

• Developed a flexible economic model based on a stable herd age structure at equilibrium.
• Integrated various longevity definitions (herd life, productive life, lactations, stayability) into the model.
• Utilized Iranian production and economic data for parameterization and estimated economic weights for traits.

Main Results:

• Estimated economic weights for milk, fat, protein yield, productive life, herd life, survival, lactations, days open, and somatic cell score (SCC).
• Excluding longevity from breeding goals resulted in the lowest genetic gain.
• Indices enhancing productive life via indirect selection on fore udder conformation yielded the greatest genetic progress.

Conclusions:

• The flexible approach effectively estimates economic values for multiple longevity definitions.
• Selection for productive life, especially through indirect selection on fore udder traits, enhances longevity, production, and reduces SCC.
• Incorporating longevity traits into selection indices is vital for maximizing overall genetic improvement in dairy cattle.