This thesis approaches the selection and comparison of 13 different growth models for describing weight gain of pets and livestock by using the Akaikes Information Criterion (AIC). In total 49699 data points of 5188 piglets recorded between 2007 and 2013, 38623 body weight records of 4046 Fleckvieh bulls collected between 1975 and 2013, 4450 data of 424 Braunvieh bulls recorded from 1986 to 2013, 281 data points of 47 bulls of the breed Charolais gathered between 2008 and 2012, 4189 body weight records of 509 puppies of the hunting dog breed Brandlbracke collected between 2003 and 2014 and 4142 data of 297 fattening pigs recorded between 2008 and 2012 were considered. Applying Akaikes Information Criterion the following mathematical growth models were compared: proportional, linear, quadratic, quadratic/zero, parabola, cubic, exponential, restricted exponential, logistic, von Bertalanffy, Parks, Richards and a two linear model. Among these models the model of von Bertalanffy had the best fit for the puppies and the piglets pre-weaning. In an overview of the piglets data the two linear model was favored by the AIC in 13 of 16 analyses of the data set. For the fattening pigs the cubic model had the smallest AIC and therefore was most suitable. The Richards model showed the best fit for the Fleckvieh and Braunvieh bulls. Based on the relatively short period for the measuring of the weight gain data of the Charolais bulls no statement could be made regarding an optimal model.