Contreras Huamaní, MijaílMendoza Leiva, César JorgeGuzman Santaria, HamiltonPalomino Guerrera, WalterQuispe Ccasa, Hurley Abel2026-10-162026-10-162026-08-11Contreras Huamaní, M., Mendoza Leiva, C. J., Guzman Santaria, H., Palomino-Guerrera, W., & Quispe-Ccasa, H. A. (2026). Evaluation of the response of creole cows (Bos taurus) to two fixed-time artificial insemination protocols in the High-Andean region of Ayacucho, Peru. Brazilian Journal of Veterinary Medicine, 48, Article e000326. https://doi.org/10.29374/2527-2179.bjvm0003262527-2179http://hdl.handle.net/20.500.12955/3328Unlike specialized breeds, High-Andean Creole cattle have developed a remarkable adaptability and hardiness to challenging high-altitude conditions, albeit at the expense of productivity. However, the efficiency of their reproductive performance under estrus synchronization protocols for fixed-time artificial insemination (FTAI) remains scarcely addressed. This study aimed to evaluate the response of Creole cows to two FTAI protocols in the districts of Chuschi (Cangallo) and Chipao (Lucanas), Ayacucho, Peru. From a sample of 60 Creole cows (identified by phenotype and coat color), with uniform body condition scores and management system, 35 were synchronized using a three-handling protocol (T1: estradiol cypionate and Bovine Intravaginal device (BID) removal on day 8), and 25 using a four-handling protocol (T2: BID removal on day 7 and estradiol benzoate on day 8). The cows were inseminated using thawed semen from Fleckvieh and Brown Swiss bulls, the latter belonging to the genetic nucleus of the Instituto Nacional de Innovación Agraria. Estrus detection rates ranged from 88.6% to 80.0%, yielding pregnancy rates of 57.1% and 56.0% for T1 and T2, respectively (p>0.05). No significant effects of protocol, age, number of calvings, body condition score, or bull breed were found on estrus detection, pregnancy, or calf sex (p>0.05). However, cows with a corpus luteum had 7.1-fold higher odds of pregnancy than those presenting only follicles (p<0.05). In conclusion, both FTAI protocols demonstrated comparable reproductive performance; however, the three-handling protocol with estradiol cypionate emerges as the preferred option due to its lower cost and greater operational simplicity under challenging High-Andean conditions.application/pdfenginfo:eu-repo/semantics/openAccesshttps://creativecommons.org/licenses/by/nc/4.0/High-andean livestock farmingGanadería altoandinaEstrus synchronizationSincronización de celoEstradiol cypionateCipionato de estradiolCorpus luteumCuerpo lúteoReproductive efficiencyEficiencia reproductivainfo:eu-repo/semantics/articlehttps://purl.org/pe-repo/ocde/ford#4.03.01https://doi.org/10.29374/2527-2179.bjvm000326Artificial insemination, Inseminación artificial; Cows, Vacas; Pregnancy, Gestación; Progesterone, Progesterona; Semen