Single-Step Breeding Value Estimations and Optimum Contribution Selection in Endangered Dual-Purpose German Black...

Area of Science:

• Animal Genetics
• Quantitative Genetics
• Genomic Selection

Background:

• German Black Pied cattle (DSN) require efficient breeding strategies for dual-purpose traits.
• Genomic selection offers advanced tools for improving livestock populations.
• Evaluating breed-specific SNP chips alongside commercial ones is crucial for optimizing selection.

Purpose of the Study:

• To conduct single-step genomic predictions in DSN cattle using a DSN-specific SNP chip (DSN_200K) and a commercial chip (50K).
• To apply estimated breeding values (EBVs) from these predictions in ongoing optimum genetic contribution (OGC) selection.
• To compare the effectiveness of the DSN_200K chip against the 50K chip for genetic improvement.

Main Methods:

• Single-step genomic predictions were performed for protein percentage (Pro%), fat-to-protein ratio (FPR), and stature (STAT).
• Genotyping was conducted using both DSN_200K and 50K SNP chips on 2797 DSN animals.
• OGC selection was applied to a pool of 1125 bull sires and bull dams, with varying genetic relationship constraints.

Main Results:

• Heritabilities were high for Pro% (0.69) and STAT (0.78), but low for FPR (0.11).
• The choice of SNP chip had minor effects on variance components, heritabilities, and EBVs.
• Relaxing the genetic relationship constraint in OGC selection improved average EBVs and increased genetic diversity, with optimal gains at a 0.06 constraint.

Conclusions:

• The DSN_200K SNP chip offers marginal additional value compared to the 50K chip for DSN cattle genomic predictions.
• OGC selection with a 0.06 genetic relationship constraint is recommended for balancing genetic gain and diversity in DSN cattle.
• The study demonstrates the utility of genomic tools for enhancing breeding schemes in dual-purpose cattle breeds.