The model is composed of two modules: a basic nutritional model describing growth in pigs and a specific model for lipid growth and FA composition (Fig. 1). The basic growth model serves as a general framework on which the lipid model is built. For the purpose of the current study, a slightly modified version of the model of de Lange (1995) was used. It is acknowledged that this model has limitations that may affect the outcome of the overall model predictions (Black, 1995 and Moughan, 1995). The choice for this model was based mainly on its simplicity of representing nutrient partitioning.