EFFECTS OF HEAT DETECTION, CONCEPTION RATE, AND CULLING POLICY ON REPRODUCTIVE-PERFORMANCE IN DAIRY HERDS

A simulation model of the reproductive process in dairy herds was developed to examine the effects of heat detection, conception rate, and culling policy on measures of reproductive performance. Twenty-one 65-cow herds were simulated to quantify over 10 yr changes in days to first service, days open, calving interval, number of services required annually, and annual culling rate attributed to strategies of reproductive management. Increasing heat detection shortened first service interval, days open, and calving interval. Improved conception rate and earlier culling for reproductive failure decreased number of annual services required by herds and increased annual culling rate. Costs of implementing such management strategies were defrayed by savings in annual insemination and replacement costs alone. Although the model was insufficient to determine optimum reproductive management strategies, it did indicate relative merits of improvement to current typical dairy herd management policies. © 1979, American Dairy Science Association. All rights reserved.