How does the proved sire system rank dairy bulls?

The "proved sire" system ranks dairy bulls based on the performance of their offspring, a process known as progeny testing.1

Rather than relying solely on a bull's own characteristics, breeders evaluate a sire by analyzing the production records of his daughters. The process typically follows these steps:1

• Initial Selection: Young sires are chosen based on their pedigree and model evaluations.1
• Progeny Evaluation: To achieve high accuracy, these young sires are mated with enough cows to produce 60 to 80 daughters.1
• Performance Recording: Once these daughters reach their first lactation, their milk production records are collected.1
• Environmental Adjustment: Because environmental factors can influence milk production, these effects are statistically adjusted out of the breeding value calculations to ensure the ranking reflects the bull's true genetic merit.1
• Selection: Only the top-performing sires—often the best 10 percent—are selected for extensive use in artificial insemination to influence the next generation.12

This rigorous testing ensures that sires used for widespread breeding possess superior genetic potential for milk and butterfat production.12