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Maternally-Derived Antibodies do not Prevent Transmission of Swine Influenza A Virus Between Pigs

A transmission experiment involving 5-week-old specific-pathogen-free (SPF) piglets, with (MDA(+)) or without maternally-derived antibodies (MDA(-)), was carried out to evaluate the impact of passive immunity on the transmission of a swine influenza A virus (swIAV). In each group (MDA(+)/MDA(-)), 2 seeders were placed with 4 piglets in direct contact and 5 in indirect contact (3 replicates per group). Serological kinetics (ELISA) and individual viral shedding (RT-PCR) were monitored for 28 days after infection. MDA waning was estimated using a nonlinear mixed-effects model and survival analysis. Differential transmission rates were estimated depending on the piglets' initial serological status and contact structure (direct contact with pen-mates or indirect airborne contact). The time to MDA waning was 71.3 [52.8-92.1] days on average. The airborne transmission rate was 1.41 [0.64-2.63] per day. The compared shedding pattern between groups showed that MDA(+) piglets had mainly a reduced susceptibility to infection compared to MDA(-) piglets. The resulting reproduction number estimated in MDA(+) piglets (5.8 [1.4-18.9]), although 3 times lower than in MDA(-) piglets (14.8 [6.4-27.1]), was significantly higher than 1. Such an efficient and extended spread of swIAV at the population scale in the presence of MDAs could contribute to swIAV persistence on farms, given the fact that the period when transmission is expected to be impacted by the presence of MDAs can last up to 10 weeks.

Source: AASV


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Four Star Veterinary Service: Jason Woodworth shares swine nutrition tips during a down market

Video: Four Star Veterinary Service: Jason Woodworth shares swine nutrition tips during a down market

There’s no question the US swine industry is struggling through a down market cycle. Jason Woodworth, Research Professor at Kansas State University, spoke to attendees at the Annual Four Star Pork Industry Conference held in Muncie, Indiana in September about nutritional strategies for feeding pigs during a down market.

“Unfortunately, the goal may be to lose the least amount of money that you can during this time, and we have to look through that lens at the idea of profitability,” said Dr. Woodworth. “Our reality is that we're going to be on the bottom side of zero, and we’re trying to conserve as much as we can. I’d encourage producers to be as nimble and flexible as possible and to try to take advantage of what's going on in the market as well as what’s happening in your barns.”