Antibody response to PRRSV vaccination may help predict reproductive performance in sows

Measuring antibody response to vaccination against porcine reproductive and respiratory syndrome virus (PRRSV) could better predict sow reproductive success than common genetic selection strategies, according to research conducted at Iowa State University. The findings are published in Frontiers in Genetics.

Genetic selection in purebred herds is the primary strategy the pig industry uses to improve litter size. However, reproductive traits are strongly influenced by the environment while genetics explain only about 10 percent of reproductive outcomes, creating challenges for rapid genetic improvements influencing litter size and survival.

“Based on our findings, swine genetic companies should use antibody response data collected at the commercial level as an indicator trait to indirectly genetically improve reproductive performance in commercial crossbred and purebred sows,” said Nick Serão, assistant professor of animal science at Iowa State, lead researcher on the study.

Serão’s team investigated the relationship between the antibody response to PRRSV vaccination and several litter size traits in commercial crossbred sows. To do this, they vaccinated the non-PRRSV-infected gilts with a commercial modified live PRRSV vaccine. Blood samples were collected about 52 days after vaccination to measure antibody response to PRRSV and animals were followed for three litters.

They showed that antibody response to PRRSV vaccination is highly heritable (34%). Also, they showed that antibody response to PRRSV vaccination had high favourable genetic correlation with the number of piglets born alive or stillborn, and pre-weaning mortality. The genetic correlations were not as strong for all the traits studied, although all were in a favourable direction. They found antibody response to PRRSV is a good candidate to be used as an indicator to genetically improve these traits.

“This trait could be easily measured in commercial gilts, at reasonably low cost,” Serão said. “Fertility traits such as farrowing rate and age at first service could also be improved using this strategy.”

In pig breeding, genetic selection is performed using purebred animals in “nucleus” herds. “But immune-related traits are usually not expressed in the nucleus,” said Leticia Sanglard, an Iowa State doctoral candidate in Serão’s lab involved in the study. “One reason for this is high biosecurity in these herds: Only after animals are introduced to commercial farms are they exposed to pathogens and other stressors that challenge their immune systems and trigger expression of such traits.”

“Animals that perform better in the nucleus environment do not necessarily perform the best in commercial herds,” she said. “An indicator trait of reproductive performance collected at the commercial level that is highly heritable, such as antibody response to PRRSV, could help obtain faster genetic progress for sows’ reproductive performance.”

Article: Sanglard, L. P., Fernando, R. L., Gray, K. A., Linhares, D., Dekkers, J., Niederwerder, M. C., Serão, N. (2020). Genetic Analysis of Antibody Response to Porcine Reproductive and Respiratory Syndrome Vaccination as an Indicator Trait for Reproductive Performance in Commercial Sows. Frontiers in Genetics, 11: 1011, doi: 10.3389/fgene.2020.01011

[SOURCE: Iowa State University]