Dynamic changes and heterogeneity in technical efficiency of broiler production under African swine fever shocks: Evidence from production organization and farm size.

African swine fever (ASF) has reshaped meat demand by reducing pork supply, driving up pork prices, and triggering substitution in consumption, thereby creating a useful setting for examining changes in technical efficiency in the broiler sector. In recent years, China's broiler industry has become increasingly contract-based and larger in scale. However, under ASF shock, the effects of substitution demand on technical efficiency across different production arrangements and farm-size categories remain insufficiently understood. Using data from China's broiler industry for 2017-2024, this study applies a stochastic frontier analysis (SFA) framework to examine the impact of ASF-induced changes in substitution demand on broiler production technical efficiency and its heterogeneity. Three main findings emerge. First, technical efficiency in broiler production exhibited clear stage-specific variation, falling to a period low of 0.913 in 2018, then recovering and peaking at 0.959 in 2021, before declining again thereafter. Second, average technical efficiency was higher for contract growers (0.939) than for non-contract growers (0.924). However, during the adjustment process, efficiency gains among contract growers were smaller, and the subsequent decline was larger, than those among non-contract growers. Third, from 2018 to 2021, efficiency gains across farm-size groups followed an inverted U-shaped pattern, with the largest increase observed among medium-scale operations and the smallest among extra-large-scale operations. From 2021 to 2024, the decline followed a U-shaped pattern, with the smallest decrease among medium-scale operations and the largest among small-scale operations. These results indicate that, under ASF shock, substitution demand does not automatically translate into sustained improvements in broiler production efficiency; rather, its effects are jointly shaped by production organization, farm-size structure, and producers' adjustment capacity. This study reveals the dynamic patterns and heterogeneous responses of technical efficiency in China's broiler industry under ASF shock, and provides evidence relevant to optimizing industry organization and strengthening supply resilience.