The objectives of this study were to analyze body measurements of 75 crossbred bulls Holstein/Zebu (Ho/Z), and Brown Swiss/Zebu (BS/Z) grazing tropical forage species at two Experimental Stations La Posta (LP) and Matías Romero (MR), to determine the model or function that best fit at growth in two genetic groups, evaluate the performance in their zoometric measures in two localities and determination the body conformation variables that best estimate the hot carcass weight. In order to model the growth curves Gompertz and Logistic mathematical functions were used and the changes occurred in body shape over time were recorded. The model that best fit was associated with (Gompertz) growth parameters that were similar between genetic groups Ho/Z and BS/Z. The body conformation increased over time and was homogeneous between the crosses of both localities, but higher in the BS/Z groups from MR after 24 months of age. Variables such as final weight, body length, shoulder width and height at wither, allowed significantly to estimate the hot carcass weight of crossbred bulls kept on extensive grazing in the Mexican tropic.