Abstract Programs have been written for use on microcomputers to utilize breeding receipt data collected by AI organizations to evaluate dairy bulls for nonreturn rates. The statistical model of analysis allows the user to have up to four fixed factors, as well as herd or herd-year effects, technician effects, and service sire effects. As an example, 137,874 AI in 1991 from one organization were analyzed. Data included information from 3609 herds, 80 technicians, and 464 sires. Although AI organizations traditionally compute 60- to 90-d nonreturn rates, these programs have caused organizations to consider using shorter period nonreturn rates in order to evaluate bulls sooner. Evidence from other work indicated that the evaluations of bulls from this analysis were more highly correlated with physiological characteristics of ejaculates than simple nonreturn rates.
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