Sequential use of estrous-detection patches as a reproductive-management tool

This study investigated whether Estrotect estrous-detection patches could be used as a simple, cost-effective reproductive-management tool to identify cyclic animals before breeding, to distinguish between cows or heifers conceiving to AI versus natural service, and to determine seasonal pregnancy rate after bull removal. A secondary objective was to determine whether altering the timing of gonadorelin (GnRH) treatment in a 14-d progesterone-Select Synch synchronization protocol could reduce labor costs without reducing protocol effectiveness. Compared with cyclic status determined via ultrasonography, Chi-square analysis indicated that estrous-detection patches monitored for a 4-wk period were able to correctly identify 79% of cyclic and 86% of noncyclic heifers (P < 0.01). Estrous-detection patches were 96 and 98% accurate in identifying heifers and cows pregnant by AI, respectively. When compared with pregnancy data obtained via ultrasonography, estrous-detection patches were 76% accurate in identifying pregnant heifers and 87% accurate in identifying pregnant cows at the end of the breeding season (P < 0.01). Data indicated that accuracy of estrous-detection patches in predicting pregnancy depends upon cyclic status of the herd. Estrus was synchronized in lactating cows using a 14-d CIDR-Select Synch protocol where timing of GnRH administration occurred at time of CIDR removal (d 14) or 24 h later (d 15). In both treatments, prostaglandin F2α was given 7 d after GnRH. Estrous response and AI pregnancy rates were similar (P > 0.10), regardless of timing of GnRH treatment. Treatment with GnRH at CIDR removal reduced labor costs and animal handling.