Optimum mating systems for the myostatin locus in cattle

Area of Science:

• Animal Genetics and Breeding
• Beef Production Systems
• Quantitative Genetics

Background:

• Inactive myostatin alleles (one or two copies) are associated with increased muscularity, lean yield, and growth efficiency in cattle.
• These genetic variations can lead to reduced fat content and quality grade (marbling), but do not negatively impact meat tenderness.
• Potential disadvantages like reduced quality grade and increased dystocia necessitate exploring optimized breeding strategies.

Purpose of the Study:

• To develop a robust method for comparing the economic viability of different mating systems for cattle with varying myostatin genotypes.
• To identify optimal breeding strategies that maximize profitability by leveraging the benefits of inactive myostatin while mitigating its drawbacks.

Main Methods:

• Economic modeling incorporating variables such as retail product prices across USDA quality grades (Standard, Select, Choice), assisted calving costs, and genotyping expenses.
• Analysis of seven distinct mating systems designed to maximize profit under diverse combinations of biological parameters and economic conditions.
• Simulation of profitability based on varying market prices for different beef quality grades.

Main Results:

• Inactive myostatin use is profitable when Select grade prices are at least 80% of Choice, and Standard grade prices are at least 60% of Choice.
• Profitability increases for mating systems favoring inactive myostatin alleles as Select and Standard grade prices approach Choice grade prices.
• Seven unique mating systems were identified, each optimal for specific economic and biological parameter combinations, demonstrating no single universal best system.

Conclusions:

• Profitable implementation of inactive myostatin genetics requires either retaining beef ownership through fabrication or developing niche markets that prioritize lean yield over marbling.
• Strategic mating systems are crucial for maximizing the economic benefits of inactive myostatin alleles in beef production.
• The economic feasibility of inactive myostatin is sensitive to market price differentials between beef quality grades.