Reducing antibiotics use among smallholders: Experimental evidence from the shrimp aquaculture sector in Vietnam.

We examine effective measures to reduce the use of prohibited antibiotics among shrimp farmers in Southern Vietnam based on an econometrics approach. We implemented a randomized controlled trial with three interventions: a) providing a technical workshop, b) quantifying the unobserved residue level of antibiotics, and c) offering price premiums for higher quality shrimp, defined as the absence of major prohibited antibiotics in our study. Using three years of panel data, we estimate the intention-to-treat effects of each intervention and find that quantifying the residue level had strong positive effects in improving farmers' knowledge and practices and reducing the probability of detecting antibiotics ex post. This result is driven by those farmers who had positive detection ex ante. Our findings suggest that providing residue test results for farmers is an effective way to solve the antibiotic residue problems in aquacultural sector in developing countries. (145 words). • Quantifying residues of antibiotics improves farmers' knowledge and practices. • Quantifying residues also reduces the probability of antibiotics detection ex post. • Farmers who had positive detection ex ante changed farming practices ex post. [ABSTRACT FROM AUTHOR]