Selection for carcass and feedlot traits considering alternative slaughter end points and optimized management

Area of Science:

• Animal breeding and genetics
• Agricultural economics
• Livestock production systems

Background:

• Profitability in animal agriculture is influenced by both animal genetics and management practices.
• Current selection indexes may not fully account for the complex interplay between genotype and management variables.
• Optimizing slaughter parameters (age, weight, or fat depth) is crucial for maximizing economic returns.

Purpose of the Study:

• To investigate the impact of different management variable parameterizations on economic weights for genetic selection.
• To determine if economic weights are equivalent across various slaughter strategies (age, weight, or fat depth constant).
• To provide a framework for calculating selection indexes that accommodate diverse commercial production systems.

Main Methods:

• Defined profit as a function of animal genotype and management-controlled variables.
• Examined alternative parameterizations of management variables, focusing on age, weight, and fat depth at slaughter.
• Calculated economic weights and selection index weights for different genotype-management combinations in beef feedlot production.

Main Results:

• Economic weights for genetic variables were found to be equivalent across different management parameterizations, provided management is optimized for the current genotype.
• Selection indexes can be effectively calculated using age-constant endpoints, even when commercial slaughter is based on weight or fat depth.
• Economic and selection index weights are dependent on average genotypic means and specific management factors (feeding and marketing).

Conclusions:

• Management optimization is key to achieving equivalent economic weights for genetic selection across different slaughter strategies.
• The findings support the practical application of selection indexes for profit improvement in livestock, accommodating varied commercial realities.
• Genotype-specific management strategies are essential for maximizing profitability in livestock production.