Impact of a killed PRRSV vaccine on sow longevity in a PRRSV infected swine herd

Abstract

In porcine reproductive and respiratory syndrome virus (PRRSV)-infected farms, there is an increase in the female culling rate, mainly due to reproductive problems and culling of young females. This has significant economic importance, as the low female culling rate is an important management factor. In the present study, in a farrow-to-finish farm with 1100 sows, all gilts and sows were vaccinated with a PRRS killed virus (PRRS KV) vaccine (PROGRESSIS (R)/Merial SAS, France) for a period of 18 months. For each gilt and sow, reproductive data were collected starting from 1-year prior until 18 months after the start of vaccination. Culling rate and the causes of culling (reproductive failure, death, old age, locomotor problems and other) were recorded. Blood samples from non-vaccinated animals were collected prior and after the start of vaccination. The purpose of this field study was to evaluate the sow longevity in a PRRSV-infected farm after their long-term vaccination with a PRRSV KV vaccine. The results indicated that the vaccination leads to a significant reduction (P<0.001) of culling rate due to reproductive failure 1.5 years after the start of vaccination and an increase of old age (P<0.001) totally 1.5 years after the start of vaccination. Eventually, culling rates due to deaths (P = 0.066), locomotor problems (P = 0.264) and other causes (P = 0.894) did not significantly differ per semester and totally prior and after the start of vaccination. In conclusion, the long-term vaccination of breeding stock with a PRRSV KV vaccine can lead to decrease of culling rate due to reproductive failure and improvement of the sow longevity.