Development of nutrigenomic based precision management model for Hanwoo steers

Area of Science:

• Animal Science
• Genetics
• Nutrigenomics
• Precision Livestock Farming

Background:

• Hanwoo feedlot systems aim for high marbling deposition using high-energy diets.
• Individual genetic variation leads to ~40% of Hanwoo steers receiving inferior quality grades despite uniform resource allocation.
• Developing nutrigenomic precision management models is crucial for optimizing Hanwoo production.

Purpose of the Study:

• To evaluate the response to divergent selection for genetic merit on marbling score (MS) under varying dietary total digestible nutrient (TDN) levels.
• To develop a nutrigenomic-based precision management model for Hanwoo steers.
• To assess the impact of genetic grouping and dietary energy on carcass quality and back fat thickness.

Main Methods:

• 111 Hanwoo calves were genotyped and grouped by estimated breeding value (EBV) for MS (high vs. low).
• Animals were managed under two dietary TDN levels (2x2 factorial arrangement) across different fattening periods.
• Carcass evaluations included MS, back fat thickness (BFT), and Korean beef quality grading standards.

Main Results:

• Direct response to selection for MS-EBV was significant, confirming the importance of initial genetic grouping.
• Dietary TDN levels did not significantly affect MS or BFT (p > 0.05), and no significant genetic-by-nutrition interaction was observed.
• Initial genetic grouping for MS-EBV increased the proportion of carcasses in higher quality grades (QG1++, QG1+) by approximately 20%.

Conclusions:

• Selection based on MS-EBV enhances marbling score without negatively impacting back fat thickness in Hanwoo steers.
• An initial genetic grouping system for MS-EBV is a key strategy for improving Hanwoo feedlot profitability.
• Further increasing dietary energy may enhance the proportion of QG 1++ animals within the high-genetic group.