<p>Artificial insemination (AI) to observed estrus is an economic biotechnology and easy to implement, however, is a tool that even today is not available to small farmers. The aim of this investigation was to determine pregnancy rates in small cattle farms in which they had not previously implemented AI, likewise, different insemination times were analyzed in relation to pregnancy rates. The research was conducted in 22 farms, the town of Ciénega Boyacá, in total 34 crossbred females Norman x Creole cows were inseminated. The AI was performed at detected estrus following the am - pm protocol. The overall, pregnancy rate obtained was 63.6 % (n = 21), in relation with the time of insemination was found that 67.6 % (n = 22) of AI were done in the afternoon, with a pregnancy rate of 65.2 %, while 32.4 % (n = 12) of AI were done in the morning with pregnancy rate of 63.6 %. In conclusion, most of the cows (67.6%) went into heat at night and were observed in heat, in the early hours of the day. However, no significant differences in the time distribution of estrus and pregnancy rates when the process is done in the morning or afternoon. Likewise, is necessary improve the heat detection and continue this type of biotechnological processes aimed at improving the bovine genetic.</p>