Milk production is a complex trait and is one of the most important criteria to consider in planning for dairy cattle improvement and to maximize the net return of dairy farms. Mathematical model of the lactation curve is useful in making management and breeding decisions and simulating the dairy enterprise because it provides summary information about dairy cattle production. Two basic sets of formulas have been used to express the configuration of the lactation curve. These are basically the linear equations and the non-linear equations. This study compared between these two basic sets using the traditional Incomplete Gamma Function (IG) as a non-linear model and a new model called the Accumulative model (Acc) as a linear model. The Acc model preformed better than the IG model according to the accuracy, which makes the Acc model is easier to use.