Mechanistic models representing physiological processes can be connected to represent whole animal systems. When the models use Michealis-Menton type kinetic equations, examples of ways to connect physiological processes are (1) including central pools (blood pool) of nutrients available for physiological processes, (2) using differential equations that represent nutrient input and output relationships for nutrient pools, and (3) assuming a physiologic process is the same across all tissues, i.e., protein synthesis. Based on the 3 example processes discussed in lecture, (1) passage of digesta through the rumen described in Baldwin et al. (1977; Agric. Syst. 2:255–288); (2) milk production by the mammary gland described in Neal and Thornley (1983; (J. Agric. Sci. Camb. 101:389–400); and (3) growth (protein synthesis) described in Oltjen et al. (1986; J. Anim. Sci. 62:86–97), participants will conduct a simulation exercise that uses these modeled processes in Molly to predict lactation performance. In the exercise, participants will observe effects of altering milk production processes on production of the dairy cow to understand how metabolic processes can be represented by mathematical equations to provide a conceptual framework that improves our understanding of animal biology.