PSVI-14 - Impact of Bacillus Subtilis and Bacillus Licheniformis on Weaning Weight and Subsequent Performance, Health and Immune Parameters When Challenged with PRRSV with and Without PRRS Vaccination

Abstract: A study was conducted examining the impact of feeding BioPlus 2B to PRRSV naïve sows during gestation and lactation on litter performance and on post-weaning performance when challenged with PRRSV in vaccinated and unvaccinated pigs. A total of 108 sows were allotted by parity and received a control diet (C) or BioPlus 2B (B2B) supplemented diet beginning a minimum of 31 days prior to farrowing through weaning. Pig weight was measured at birth and 17 days of age. At weaning, a subset of 200 pigs from each treatment were transported to a nursery and randomly allotted within dietary treatment on day 1 to a control (-V) or Ingelvac PRRS® MLV vaccine (+V), establishing treatments of C+V, C-V, B2B+V, and B2B-V. On day 21, all pigs were intramuscularly challenged with a 1-18-2 PRRS virus. Growth rate and feed intake were monitored, serological and immune measures were recorded on day 21, 28, 35 and 42, post-weaning and on day 42 gross lung lesions were recorded. Pigs from sows receiving B2B tended (P < 0.10) to weigh more at 17 days of age and 21 days post-weaning (Table 1). Prior to challenge, there were no performance differences among treatments. Post challenge, there was a V x B2B interaction with C+V, B2B+V and B2B-V pigs having higher ADG and FG (P < .05) compared to C-V. On day 42, pigs fed B2B displayed improved lung lesion scores (P < 0.05) regardless of vaccine status. PRRSV viremia, measured by PCR and qPCR decreased more quickly when pigs consumed B2B (P < 0.05). Additionally, B2B modulated PRRSV specific T-cell interferon gamma production (P < 0.05). In conclusion, pigs consuming B2B from sows fedB2B were heavier at weaning and when subjected to a PRRSV challenge post-weaning, grew faster, were more efficient, and had reduced gross lung lesions, likely due to changes in immune function.