The aim of this study was to determine the best mathematical model for growth curve in different feeding practices of slaughter Morkaraman male lambs after weaning to explain the change in live weights of lambs in the period prior to the slaughter. For this purpose, Morkaraman 45 male lambs, at 75 days of age (weaning) were selected and divided into 3 groups of 15 heading through random sampling and different feeding regimes were followed for each group. The first group was traditionally grazing in pasture alongside suckling dams in the morning and evening; the second group was fed with concentrate feeds, dried grass feeding and alfalfa as ad libitum in containment pens; the third group was fed traditionally by grazing in the pasture. Live body weight records that were collected every 15 days from birth to 135 days of age were analyzed with non-linear Brody, Bertalanffy, Logistic, Gompertz and Richards models. The model with high coefficient of determination (R²) and low mean square error (MSE) was chosen as the best model defining growth. Richards and Logistic models were the best determinants of the overall growth of lambs in non-linear models. Among the groups, the lowest MSE and the highest R² were obtained in the second group and in the Logistic model. According to this model; A, B, k, R² and MSE were found as 43.78±1.873, 8.18±0.523, 0.027±0.0012, 0.999±0.0002 and 0.41±0.060 respectively. As a result, it was observed that the second group lambs developed faster and achieved the slaughter weight at an earlier age than the other groups. The study also revealed that the additional feeding (concentrate feed, clover, fodder, milk) was a significant factor affecting the growth of the lambs.