The objetive of this study was to evaluate the effect of bypass fat in productive and reproductive parameters in bovine females indicates crosses in the Fundación livestock farm; of the parish Guasdualito Venezuela, Apure state, making a modification to Crestar® protocol. The fat by pass was provided by 52 days, to cows with an average of 3 was provided7 years of age, with no health problems and body condition from 2.75 to 3.5 (scale 1-5). The animals were inseminated into two groups and found that the average final body condition in the Gyr and crossbred cows improved; there is a positive correlation strong between the intensity and duration of heat and that the presence of the calves contributes to find animals with jealousy of short duration and low intensity.