Progeny testing and selection intensity for Holstein bulls in different countries

Area of Science:

• Animal Breeding and Genetics
• Dairy Science
• Quantitative Genetics

Background:

• Progeny testing (PT) is crucial for evaluating dairy bulls.
• International Bull Evaluation Service (Interbull) provides standardized evaluations.
• Understanding national PT program characteristics is essential for genetic improvement.

Purpose of the Study:

• To analyze and compare the characteristics of progeny testing programs for Holstein bulls across ten countries.
• To identify variations in PT program components and selection intensities.
• To highlight potential areas for improvement in international PT strategies.

Main Methods:

• Utilized International Bull Evaluation Service (Interbull) Holstein evaluations from 1995 to 2003.
• Defined bull graduation based on the second Interbull evaluation and daughter numbers.
• Analyzed data on bull age, herd size, daughter numbers, and selection intensities for various traits.

Main Results:

• Significant variation observed in mean bull age at PT decision (12 months range) and number of herds/daughters across countries.
• Countries with higher evaluation requirements generally had more herds/daughters but older bulls at PT decision.
• Graduation percentages ranged from 4.4% to 14.7%, with selection intensities around 1.0 for yield traits but varied for other traits like somatic cell score and udder traits.

Conclusions:

• National breeding goals influence selection intensities, leading to variations in PT program outcomes.
• Differences in PT program components offer insights into potential areas for optimization.
• Comparative analysis of PT programs can guide improvements in dairy cattle genetic evaluation and breeding strategies.