Performance improvement after implementation of 3FLEX® with partial depopulation in a Korean farm

PRRSv is a primary pathogen causing PRDC. But PRRSv can be controlled by piglet vaccination. To get the best result, the interval between vaccination and infection should be 4 to 5 weeks.

The purpose of this study is to obtain a PRRS noninfection period for 4 weeks after vaccination by partial depopulation of the nursery and to evaluate the efficacy of an additional PRRS vaccination of piglets to control PRRS for the whole production period.

This farm is one-site system with 150 sows. Pigs are weaned at 25 days of age(DOA) and transferred to the grower house at 53 DOA and finisher house at 120 DOA.

Pigs in group ‘A’ are vaccinated with FLEXcombo® (CircoFLEX® and MycoFLEX®) at 3 weeks of age(WOA). In group ‘B’ and ‘C’, pigs are vaccinated with 3FLEX® (FLEXcombo® and Ingelvac® PRRS MLV) at 3 WOA.

Before implementing a partial depopulation, pigs in the nursery house were transferred to the grower house (group ‘A’). During the depopulation, newly weaned piglets were raised in the farrowing house for 4weeks (group’B’) then transferred to the grower house. After finishing partial depopulation of the nursery, newly weaned piglets were transferred to the nursery (group ‘C’).

Tissue samples from necropsy and blood samples were tested by PCR and ELISA. Mortality and clinical signs were evaluated after weaning.

Nursery house mortality in ‘A’ group is 25.49%, ‘B’ group is 1.31% and ‘C’ group is 1.29%. Grower house mortality in ‘A’ group is 12.72%, ‘B’ group is 5.31% and ‘C’ group is 4.35%. Finisher house mortality in ‘A’ group is 6.03%, ‘B’ group is 2.34% and ‘C’ group is 1.82%. In group 'A', atrophy and coughing were observed. But in group 'C', there was no clinical sign in nursery. PCR results of lung tissue in group ‘A’ revealed NA type of PRRSv. PRRSv PCR positive results of blood samples in group ‘A’ were only found in blood samples of pigs 40 DOA.

In this study, we could demonstrate that after implementing partial depopulation, nursery pigs showed better performance and group ‘B’ pigs that had been transferred directly to the grower house, showed better performance against PRRS infection compare to group ‘A’. Partial depopulation of the nursery could control PRRSv in the nursery resulting in an improvement within a short period of time . However, there were still many pigs infected with PRRSv in the grower house. So the mortality was still high but could be controlled by using 3FLEX®. Interval between vaccination and infection was 4 to 5weeks due to partial depopulation. Partial depopulation is an important tool that can be used together with vaccination to control PRRS especially in case of early infection of PRRS after weaning

Disclosure of Interest: None Declared.