Introduction: In many countries, agricultural product markets face the challenges related to pricing inefficiencies across various sectors and marketing channels. A major source of this inefficiency is asymmetric price transmission, where price increases and decreases at one level of the marketing chain are transmitted to other levels at different rates. The impact of price changes at one market level on others (i.e. how price transmission functions) significantly affects the welfare of producers, marketing agents, and consumers. Asymmetric transmission benefits intermediaries while harming producers and consumers by imposing additional costs. Examining vertical price transmission reveals power imbalances among supply chain actors, allowing researchers to identify bottlenecks, market power, and inefficiencies within the system. Furthermore, researchers can assess the impact of policies (like subsidies) on supply chain actors by analyzing how these policies affect price transmission. Understanding vertical price transmission is crucial for designing effective pricing policies and ensuring market stability. Analyzing how price shocks propagate through the chain improves decision-making, regulations, and stakeholder support, ultimately leading to improved food access, price stability, and enhanced food security. Therefore, considering the importance of price transmission, this study aimed at evaluating price transmission behavior at different levels of the chicken meat market from April 2014 to March 2024. Additionally, to assess the impact of the COVID-19 pandemic and the elimination of preferential currency, two dummy variables were added to the model. For the COVID-19 dummy variable, a value of one was assigned to the months from March 2020 to March 2022, and zero to all other months. Similarly, for the preferential currency elimination dummy variable, a value of one was assigned to the months from May 2022 to March 2024, and zero to all other months.
Materials and Methods: To investigate the price transmission, the stationarity of the variables and the cointegration between them were first tested. Subsequently, the causal relationship between the variables was examined. Finally, the Error Correction Model (ECM) was applied to investigate the transmission process. To account for structural breaks resulting from different price shocks, Fourier approximation was used at all stages of the analysis. This study employed monthly time series data from April 2014 to March 2024 to examine price transmission across different levels of the chicken meat market.
Results and Discussion: The results of the unit root test indicated that chicken prices at all three levels were first-order stationary. The findings from the Fourier cointegration test, which examined the cointegration relationships between chicken prices at different levels, indicated a number of causal relationships as follows:

Between the price of live chicken at the poultry farm and the price of chicken meat at the slaughterhouse.
Between the price of chicken meat at the slaughterhouse and the price of chicken meat at the retail level.
Between the price of live chicken at the poultry farm and the price of chicken meat at the retail level.

These results suggest a bidirectional causal relationship at various levels of the chicken meat market. In other words, the price of chicken at any level is influenced not only by the prices at other levels but also exerts an influence on them. Consequently, the effects of various shocks, whether positive or negative, are not limited to production but are transmitted to the prices at the slaughterhouse level and consumer prices. In addition, shocks in the market also affect the prices at the farm (poultry farms) level. The study findings indicated that the elasticities of price increases were greater than those of price decreases at different levels, and the symmetry test in the short run revealed the evidence of asymmetric price transmission. In contrast, the long-run symmetry test showed that the price transmission was symmetric across various market levels. The results also highlighted some positive effects of the COVID-19 and the elimination of preferential currency on chicken price changes at the retail level, suggesting that the COVID-19 pandemic and the elimination of preferential currency had increased the price volatility. However, considering the estimated elasticities, the response of chicken meat price changes at the retail level to the COVID-19 pandemic and the elimination of preferential currency was relatively negligible.
Conclusion and Suggestions: Despite the asymmetric price transmission in the short run, it is evident that government intervention is necessary to correct the pricing process. Therefore, it is recommended to ensure the supply of poultry inputs at reasonable prices, support domestic production of poultry inputs, allocate bank facilities under favorable conditions for poultry farmers, and improve the supply chain to reduce production costs. Due to the asymmetry in price transmission in the chicken meat market, consumers often pay more than the total cost, resulting in losses, while marketing agents benefit from price fluctuations and uncertainty. To support the consumers, the government can implement policies such as stockpiling and distributing chicken during shortages or price increases and setting price ceilings for chicken during critical and necessary times.