Para evaluar la respuesta de vacas sometidas a dos protocolos de sincronizacion de la ovulacion, se utilizo 318 vacas mestizas Holstein de seis asociaciones de pequenos productores de leche de los municipios de Buesaco, Yacuanquer, Ospina, Sapuyes, Cumbal y Guachucal en el departamento de Narino, Colombia, beneficiarias del convenio interadministrativo No. 20130369, las cuales fueron evaluadas reproductivamente por ultrasonido, divididas aleatoriamente en dos grupos de 159 vacas cada uno. Al grupo uno (T1) se aplico un implante intravaginal con1,3 gde progesterona, mas 2 mg de benzoato de estradiol (BE); al retiro, siete dias despues, se administro 150 mg de D-Cloprostenol (PgF2α) y, 24 horas mas tarde, 1 mg de benzoato de estradiol. Para el grupo 2 (T2), se aplico el mismo implante mas 2 mg de BE y, al retiro, 7 dias despues, se utilizo 150 mg de PgF2α mas 500 UI de gonadotrofina corionica equina (eCG) y, al momento de la inseminacion, se aplico 100 mg de gonadorelina (GnRH). Todas fueron inseminadas 56 horas despues de retirado el implante y el diagnostico de prenez se dio a los 50 dias de la inseminacion artificial a tiempo fijo (IATF). Se utilizo analisis de varianza (ANOVA) para los resultados y la separacion de medias con prueba Tukey. Se encontro diferencias estadisticas significativas entre los dos tratamientos (p<0,05), en favor del T2 (eCG +GnRH), con una tasa de prenez del 69,13% con respecto al T1 (BE) de 36,26%, para los seis municipios. Se concluyo que la administracion de eCG, despues del uso de un dispositivo de progesterona, puede aumentar la sincronia de ovulacion y mejorar la tasa de concepcion en protocolos de IATF, con efectos positivos bajo condiciones de estres o en vacas con condicion corporal menor a 2,75, como las de pequenos productores de leche. Palabras clave: gonadotropina corionica equina, sincronizacion del celo, ovulacion EVALUATION OF TWO PROTOCOLS FOR SYNCHRONIZATION OF OVULATION IN COWS OF SMALL MILK PRODUCERS IN SIX MUNICIPALITIES IN THE DEPARTMENT OF NARINO, COLOMBIA ABSTRACT To evaluate the response of cows subjected to two protocols for synchronization of ovulation, 318 Holstein crossbred cows belonging to six associations of small milk producers from the municipalities of Buesaco, Yacuanquer, Ospina, Sapuyes, Cumbal and Guachucal in the department of Narino, Colombia. They are beneficiaries of the inter-administrative agreement Nr. 20130369, which were reproductively evaluated by ultrasound, and randomly divided into two groups of 159 cows each. The group one (T1) was put an intravaginal implant with progesterone 1.3 g plus 2 mg of benzoate of estradiol (BE); seven days later, when the implant was removed, 150 mg of D-Cloprostenol (PgF2α) were used; and after 24 hours 1 mg of estradiol benzoate was applied. For Group 2 (T2), the same implant plus 2 mg of BE was applied, and at the implant removal, 7 days later, 150 mg of PgF2α plus 500 IU of equine chorionic gonadotropin (eCG) were applied; besides, at the time of insemination, 100 mg of gonadorelin (GnRH) were used. All the cows were inseminated 56 hours after removing the implant and the diagnosis of pregnancy was done at 50 days of timed artificial insemination (TAI). Analysis of variance (ANOVA) was applied to the results and the Tukey test was used to separate the means. The results showed significant statistical differences between the two treatments (p < 0.05), favoring the T2 (eCG GnRH) with a rate of pregnancy of 69.13% with respect to the T1 (BE) with 36.26%, for the six municipalities. It was concluded that the administration of eCG after using a device of progesterone, can increase the timing of ovulation and improve the rate of conception in IATF protocols with positive effects under stress conditions, or with corporal conditions less than 2.75, as in the small milk producers.