Repeat breeder syndrome in dairy cows: infl uence of breed and age on its prevalence and the success of a hormone therapy*

Th e aim of this study was to establish the prevalence of repeat breeder syndrome (RBS) in diff erent breeds and reproductive ages of cattle in central Croatia and to assess the eff ectiveness of hormone therapy as a treatment option. A total of 1088 dairy cows were observed, 218 heifers and 870 multiparous cows. Aft er the third unsuccessful artifi cial insemination (n = 164) and a thorough clinical and gynecological examination, the cows were tested for sexually transmitted diseases. An RBS diagnosis was based on failure to conceive, negative laboratory tests for sexually transmitted diseases, and the absence of other reproductive disorders. Th e highest prevalence of RBS was found in crossbreed cows, followed by the Holstein-Friesian, Red Holstein, and Simmental breeds. RBS was not detected in cows of the Swiss Brown breed. Th e prevalence of RBS was signifi cantly higher in heifers in comparison to multiparous cows. Cows diagnosed with RBS were administrated hormone therapy based on the Double Ovsynch protocol with applications of gonadotropin-releasing hormone (GnRH) and a prostaglandin analogue (cloprostenol). Th is hormone treatment resulted in a higher conception rate in all treated animals and signifi cantly impacted the culling rate due to the subfertility.