Feed conversion ratio of Litopenaeus vannamei farming in China: evidence from multi-province surveys (2016–2023)

The feed conversion ratio (FCR) is a key indicator of efficiency and sustainability in aquaculture, yet existing evidence on its farm-level determinants remains dominated by nutritional experiments, with little rigorous identification of the causal effects of managerial inputs or their heterogeneity across production regimes. Using farm-level survey data from 222 Litopenaeus vannamei farms in four major Chinese producing provinces over 2016–2023 (n = 382 farm-cycle observations), we applied propensity score matching (PSM) with subsample heterogeneity analysis, validated by Rosenbaum bounds and OLS interaction tests, to identify the effects of branded-feed adoption and technical-service access on FCR. Four findings emerge. First, in the pooled sample, both branded feed (ATT = −0.31, p < 0.05) and technical services (ATT = −0.24, p < 0.05) significantly reduce FCR. Second, among traditional pond farmers, branded feed yields a substantial efficiency gain (ATT = −0.528, p < 0.01), whereas technical services do not. Third, among industrialized farmers, the pattern reverses: technical services significantly reduce FCR (ATT = −0.376, p < 0.01), whereas branded feed has no detectable effect. Fourth, Rosenbaum bounds confirm that the significant ATTs withstand hidden bias up to Γ ≈ 2.8–3.0, and OLS interaction tests independently replicate the reversal. The evidence supports a complementarity-matching hypothesis: the marginal value of a modern input depends on whether it relieves the binding constraint of the production regime. The findings inform a differentiated extension policy for sustainable shrimp aquaculture.