A NEW GENERAL CONCEPTUAL APPROACH TO MODELING THE LIVESTOCK SECTOR: AN APPLICATION TO THE JAPANESE SWINE-PORK SECTOR

Many livestock sector models have limited coverage of relevant variables, and are somewhat ad hoc in their choice of what should be specified as behavioral equations. This study develops a generic conceptual approach to modeling the livestock sector that provides consistent rules of specification and better coverage of variables. This approach is then applied to the swine-pork sector of Japan. The new approach departs significantly from existing models. The structure clearly differentiates stock and flow variables; only flow variables have behavioral specifications and stock variables are accounting identities; flow variables are expressed in rates rather than levels; logistic functions are used in most flow variables to automatically impose biological-technological limits; and swine slaughter number and weight are disaggregated into sow and other swine (i.e., gilt-barrow).The estimated Japanese swine-pork model has good fit, no serial correlation, significant coefficients, correct signs, and is better able to capture both the mean and variability of all endogenous variables.