Sow parity has no effect on incidence and timing of influenza in piglets

Sow parity appears to have no effect on the incidence and timing of influenza infection in piglets, indicates a study presented at the 2017 annual meeting of the American Association of Swine Veterinarians.¹

Researchers conducted a study based on the premise that piglets from primiparous sows — those that have delivered one litter — would be more likely to be infected with influenza and at a younger age due to lower maternal antibody titers compared to piglets from multiparous sows.

After randomly selecting 15 gilts and 15, four-parity sows from three farrowing rooms on a commercial sow farm with endemic H1N1 influenza, they tested five litters from each parity group, said Megan E. Bloemer, a student at the University of Illinois.

Based on polymerase chain reaction testing of pooled nasal-swab samples, they found that both parity groups had seven positive litters over the course of the study, sponsored by Zoetis.

Although parity had no effect on the incidence and timing of influenza infection in pigs, the researchers did find that age was highly significant. The number of litters testing positive increased as piglet age increased starting at 10 days of age onward, and the incidence was the same for both the gilt- and sow-parity groups, Bloemer said.

“This study does not support managing populations according to parity for influenza,” Bloemer said. “Practitioners should continue to vaccinate the whole sow population since pigs from primiparous litters do not appear to be more likely to be infected or infected at a younger age with influenza than multiparous sows.”

1. Bloemer M, et al. Impact of sow parity on the influenza A (IAV-S) infection timing of the suckling pig in an endemic herd. . In: Proceedings of the 48^th Annual Meeting of the American Association of Swine Veterinarians (February 25-28, 2017). Page 242.