Using a Stochastic Model to Evaluate Swine Production Management with Paylean I: Model Development and Optimal Management Strategies

The economically optimal use of ractopamine (RAC, Paylean) had been examined using a growth model for a single pig with average growth properties (Li et al., 2002). In reality, however, pigs are produced in groups, where, with All-in/All-out (AIAO) management, the group size equals the barn capacity. The turn-over of the barn depends on the marketing day of the last batch, not the pig with the average growth rate. In this research, the management of pig production with Paylean was investigated for a group of pigs using a stochastic growth model, which allowed each individual pig to have a unique body weight growth curve and carcass composition growth curve, and meanwhile reproduced the population mean and variancecovariance growth structure (Schinckel et al., 2003a). A bio-economic model was developed based on a stochastic growth model (Schinckel et al., 2003a), which incorporated the economic optimization principles of livestock replacement, swine growth under limited dietary lysine intake, and swine growth response to Paylean (Schinckel et al., 2003b). This stochastic bio-economic model was used to derive the optimal production and marketing decisions for grow-finish swine production with Paylean, which include both dietary lysine management and Paylean management. Because the model simulated realistic industry practices, the derived management strategies were more powerful than those derived from a single pig with an average growth curve.