[Mathematical simulation of the selection process in a dairy herd]

Area of Science:

• Animal Science
• Dairy Cattle Genetics
• Quantitative Genetics

Context:

• Study conducted in a large-scale dairy unit (2000 stable places).
• Evaluated selection strategies based on parentage and individual performance.
• Considered age structure, genetic gain, and average production.

Purpose:

• To determine the optimal intensity of selection for parentage and individual performance in dairy cows.
• To analyze the impact of selection intensity on genetic gain and average milk yield.
• To assess the relationship between selection intensity and the genetic efficiency of cow dam selection.

Summary:

• Maximum genetic gain was achieved by selecting 66% of heifers for parentage and culling 20% of first-calvers based on performance.
• Increased selection intensity led to a 3-6% rise in average milk yield.
• Higher selection intensity decreased the genetic efficiency of cow dam selection by 10-37%.

Impact:

• Provides insights into effective breeding strategies for dairy herds.
• Highlights the trade-off between increased milk production and genetic efficiency.
• Informs dairy management decisions for maximizing herd performance and genetic improvement.