Breeding delays determine the wavelength of the pork cycle

Abstract

Abstract The pork cycle exhibits persistent oscillations in prices and production with a wavelength of three to six years. We develop a system dynamics model in which cyclical behaviour arises endogenously from biological delays and a simple adjustment rule, without the explicit modelling of price or forward-looking optimization from decision-makers. The model reproduces the cyclical component of Dutch pork prices, matching its wavelength and turning points, and explains the gradual shortening of the cycle through technological changes that reduced production lead times. Sensitivity analysis further separates the parameters that govern the cycle’s wavelength from those that govern its amplitude, and identifies policy levers acting on each. Our findings do not imply that prices are irrelevant; rather, they highlight that a significant part of the pork cycle is structural, with prices primarily reflecting underlying production delays. This perspective complements rational-expectations models and clarifies why similar ‘pork cycle’ patterns appear in other industries with long lead times.