Accelerated Conception Evaluation (ACE) is a sire fertility index developed by Accelerated Genetics by collecting data from dairies across the United States. ACE uses a complex statistical model that accounts for both cow and environmental factors such us parity, number of inseminations, season of breeding, level of milk production, year of breeding, farm and days in milk; the response variable is sire fertility. The reproduction results included in the analysis are based only on actual pregnancy checks, not non-return rates.