Although Bill enjoyed his work as a classifier, he felt frustrated that he could only evaluate what a dairy breeder already had in his herd. His goal was to figure out how breeders could mindfully and consistently produce the best possible offspring from the good animals they had.

Using detailed worksheets based on the true type classification score card, Bill Weeks and his associates documented the form and function of thousands of dairy cows and bulls. After studying this documentation, Bill identified naturally occurring patterns in the way animals’ body parts are formed and function together. He first used the terms “round” and “sharp” to describe the qualities cows need and bulls provide in a simple way that breeders could use when making matings. After several years, Bill realized that the terms “round” and “sharp” alone did not adequately describe the relationship of body parts that determine the form and function of an animal, so he further refined the aAa® Animal Analysis system to include the six aAa® numbers we know today.

aAa® Animal Analysis has been used by North American dairy breeders since 1950, expanding over the years into Europe, New Zealand and Australia. The aAa® service mark is used by aAa® approved analyzers in the United States, Canada, Mexico, Australia and New Zealand, and the Weeks® service mark is used by aAa® approved analyzers in European countries and Japan. Most major AI companies in North America, Europe and Oceania have their bulls analyzed and make this information available to customers.