Dairy cattle breeds of European origin stand out for their high productive and reproductive efficiency in temperate climates, but they usually do not present this efficiency in tropical climate, in conditions such as high temperature and humidity, high incidence of endo and ectoparasites and low level of management. On the contrary, Zebu breeds in selection programs to increase milk production are naturally adapted to such conditions, that is, they produce well in less sophisticated managerial practices and have natural resistance to endo and ectoparasites. These breeds, however, have less milk production by lactation, which can result in compromised economic efficiency of production systems. Thus, the use of crossbred animals, having as main basis the exploration of heterosis and complementarity between European (more productive) and Zebu (more adapted) breeds, has become a widespread procedure in milk production systems in Brazil , especially in regions with breeding conditions similar to those mentioned above. In the past, in most milk production systems with crossbred animals, unselected Zebu females were mated with Holstein males and the results achieved, although better than those obtained by performing random mating, were below the expected potential, since the Zebu breed used did not have any contribution to additive variance of genes because it had not yet undergone a genetic selection process. On the other hand, currently, in the Gyr breed, after more than 30 years of intense work of genetic improvement, there is availability of semen from bulls of high genetic merit, inclusively having consolidated genomic selection, enabling the use on a larger scale of proven Gyr bulls, mated with Holstein cows or the use of Holstein bulls mated with Gyr cows of high genetic merit. Thus, with both breeds contributing with additive genetic inheritance, there is great expectation in obtaining more productive, genetically superior animals, which can greatly contribute to improving the technical and economic efficiency of milk production systems. In addition, there is a good supply of females at affordable prices from both breeds, enabling the production of F1 or half-blood animals, through mating using proven breeding semen, either through artificial insemination, embryo transfer (TE) or in vitro fertilization (IVF). With the reduction of the cost of the techniques used to produce the embryos, the use of biotechniques TE or IVF becomes progressively an economically viable option for farmers. In milk production systems with crossbred animals, most of the farmers have doubts about the best breeding strategy, that is, mating Holstein females with proven Dairy Gyr bulls or mating Dairy Gyr females with Holstein bulls. No research results were found in the literature to answer this question regarding the aspect of milk production. It is already known that the Zebu breed responds better to the in vitro fertilization technique than the Holstein breed. Thus, this project aimed to evaluate the technical efficiency of two production strategies of first generation half-blood animals or F1, through TE or IVF, based on the comparison of the productive, reproductive and economic performance of two genetic groups obtained from two breeds, Dairy Gyr and Holstein, for milk production systems based on continuous replacement with F1 females. Two groups of F1 females were assembled, one named GxH, resulting from embryos of Dairy Gyr female donors with semen of Holstein bulls and another one named HxG, resulting from embryos of Holstein female donors with semen of Dairy Gyr bulls. In the first phase, evaluations of the response to the reproductive biotechniques used for the generation of F1 animals were carried out comparing the two genetic groups and also the efficiency of the embryo transfer process, fresh or frozen, in crossbred animals. Subsequently, comparisons were made using IVF. In the production of embryos, Dairy Gyr female donors from the herds of Brasília, Getúlio Vargas, Terra Vermelha and Calciolândia farms and Holstein female donors from Embrapa Dairy Cattle's herd were used. The results of embryo production, blastocysts, pregnancy at 30 and 60 days, births of males and females and duration of pregnancy for both groups (GIR = Dairy Gyr female donors or HOL = Holstein female donors) and the respective pregnancies showed no differences between groups in the percentage of embryos produced (81% for GxH, and 74.3% for HxG). However, the total number of blastocysts produced was 2.39 times higher in the GIR group and the average number of embryos produced per session was higher in the same group. Subject to the availability of recipients, 207 embryos were transferred. Pregnancy rates between the GxH and HxG groups were similar at 30 days (47.2% x 41.5%) and higher than 60 days for GIR donors (42.9% x 33.8% ). The percentage of births of male calves did not differ between groups, despite being numerically higher in the HOL group (8.1% x 14.3%). The duration of pregnancy of 160 females produced by PIVE and by superovulation was 6.52 days longer in the HOL group (287.3 HxG group and 280.8 GxH group), suggesting an effect of maternal or paternal contribution on this characteristic. Therefore, the present study demonstrated that the production of F1 animals in tropical regions has better reproductive performance using Dairy Gyr female donors, when compared to the use of Holstein ones. Females in the GxH group had higher average weight than females in the HxG group in the periods of 451 to 540 days, 541 to 630 days and 631 to 720 days. After this period, the weight difference between the two groups of females was reduced. The conclusions supported by this work are that, reproductively, it is much more feasible to produce F1 or half-blood first generation animals, from donors of the Dairy Gyr Zebu breed than from donors of the Holstein breed. On the other hand, milk production was higher in F1 daughters when Holstein donors are used. This result, from the production point of view, may not be repeated nowadays, in view of the possibility of using genomics in the choice of both donors and bulls, ensuring greater standardization of the genetic level between groups. Therefore, one must consider the result as a preliminary work that must be repeated in order to have more accurate conclusions.