RESUMO
Costs of 14 methods to detect estrus were compared under simulated commercial dairy situations using artificial insemination. Alternative methods were twice or thrice daily visual observation and factorial combinations with various estrous detection aids [teaser bull, heat mount detector, and tail paint (also in combination with visual observation only during routine chores), estrous synchronization by prostaglandin F2 alpha, estrous synchronization plus heat mount detector]. A sensitivity analysis was used to compare tail paint and heat mount detector methods. Total costs for labor and other inputs were estimated for alternative 120-cow dairy herds with cumulative conception rate greater than or equal to 90% by considering five labor wage rates, four first-service conception rates, and three detection rates for each estrous detection method. Heat mount detector and tail paint methods with visual observation only during routine dairy chores always had lowest cost when average wage rate exceeded @2.25/h. To make heat mount detectors competitive, corresponding detection rate would have to be at least 10% higher than for the tail paint method. Unaided visual observation with two checks/d was less expensive than heat mount detector methods when labor had few alternative demands and cost less than $2.25/h. These methods were generally less than half as costly as teaser bull and prostaglandin alternatives.