Genetic parameters for first milk production and composition traits for Holsteins using multivariate restricted...

Area of Science:

• Animal Genetics
• Dairy Science
• Quantitative Genetics

Background:

• Understanding genetic and phenotypic correlations is crucial for effective dairy cattle breeding programs.
• Estimating these correlations helps in selecting for multiple traits simultaneously, optimizing genetic gain.
• Previous studies have provided insights, but ongoing analysis with updated data refines these estimates.

Purpose of the Study:

• To estimate heritabilities and genetic/phenotypic correlations among milk, fat, and protein yields and percentages in Holstein cattle.
• To utilize a large dataset of first lactation records for robust statistical analysis.
• To compare findings with previous research in the same population.

Main Methods:

• Multivariate Restricted Maximum Likelihood (REML) analysis was employed.
• A sire model was used, accounting for genetic relationships and sire groups.
• Proven sires were included as fixed effects in the model.

Main Results:

• Heritabilities for milk, fat, and protein yields were .29, .31, and .25, respectively.
• Heritabilities for fat and protein percentages were high (.65 and .61).
• Significant genetic correlations were observed between yields and percentages, with notable positive correlations between fat yield and fat percentage (.56).

Conclusions:

• Genetic and phenotypic correlations provide valuable information for dairy sire selection.
• High heritability for fat and protein percentages indicates strong additive genetic control.
• The findings support previous estimates and contribute to optimizing breeding strategies for improved dairy production traits.