Effects of herd closure and medication programs on the infection of NADC30-like PRRSV in pig farms.

Abstract

Importance: The porcine reproductive and respiratory syndrome virus (PRRSV) poses a significant threat to swine production, particularly with emerging strains such as the highly virulent NADC30-like strain.

Objective: This study examined the impact of PRRSV NADC30-like strains on pig farms in Fujian, China.

Methods: The effectiveness of strategic management protocols, including herd closure, medication programs, monitoring of processing fluids (pig testicular fluid), and collection of production data, were analyzed. The prevalent strain in the pig farm was identified as a NADC30-like strain of the PRRSV through genetic sequencing comparison analysis.

Results: The quantitative real-time reverse-transcription polymerase chain reaction results showed that the PRRSV cycle threshold (Ct) values of the processing fluid samples were relatively low from September to early October 2021. After implementing the intervention measures (October 2021), the Ct value increased gradually and reached a negative in March 2022, lasting six months. In addition, the average survival rate of the pigs before the intervention was 84.1%, while the average survival rate after the intervention was 93.1%.

Conclusions and relevance: The use of 12-month intervals for pig herd closure, drug planning, and other strategic management agreements (multi-point production and active monitoring of production data, McREBEL) helped stabilize the subsequent pig farm production, providing a basis for clinical disease prevention and control.