Incorporating heifer feed efficiency in the Australian selection index using genomic selection

Area of Science:

• Animal genetics and breeding
• Quantitative genetics
• Dairy cattle production

Background:

• The Australian Profit Ranking (APR) index is crucial for optimizing dairy herd profitability.
• Residual Feed Intake (RFI) is a key trait for feed efficiency in livestock.
• Integrating RFI into selection indices can enhance economic returns and sustainability.

Purpose of the Study:

• To evaluate the economic benefits of incorporating Residual Feed Intake (RFI) into the Australian Profit Ranking (APR) index.
• To estimate genetic parameters and genomic correlations for RFI and other economically important traits in Holstein heifers and bulls.

Main Methods:

• Utilized a multitrait selection index approach to assess the economic impact of RFI inclusion.
• Estimated heritabilities and genomic correlations for RFI, Dry Matter Intake (DMI), and APR traits using a Bayesian framework.
• Employed single nucleotide polymorphism (SNP) data for genomic correlation estimations.

Main Results:

• Heritability estimates for DMI and RFI were 0.44 and 0.33, respectively, with a nonsignificant genomic correlation (0.03) between them.
• Genomic correlations between feed efficiency traits and milk production traits were near zero (-0.11 to 0.10).
• Inclusion of RFI in the APR index is predicted to reduce annual feed consumption by 1.73 million kg, yielding A$0.55 million in savings, and improve calving interval by 0.53 days/cow/year.

Conclusions:

• Incorporating Residual Feed Intake (RFI) into the Australian Profit Ranking (APR) index offers significant economic advantages through reduced feed costs.
• The study demonstrates that RFI can be effectively integrated into breeding programs to improve both feed efficiency and overall herd profitability.
• Selection on the enhanced APR index is expected to improve multiple production and fertility traits simultaneously.