The objectives of this study were to examine the effects of porcine reproductive and respiratory syndrome virus (PRRSV)
infection and vaccination on pig growth, dietary nutrient efficiency of utilization,
manure output, and emissions of CO, CH, HS, NO, and NH
gases from stored
manure. Forty-eight pigs, aged 21
d at the start of the study, were subjected to 1 of 4 treatment combinations arranged in a 2 × 2 factorial design with main factors of PRRSV vaccination and PRRSV
infection.
Body weight, ADFI,
manure output, and nutrient efficiency of utilization were assessed and gas emissions from stored
manure were determined daily from 50 to 78 d of age and for 24 d after completion of the animal phase.
Infection with PRRSV markedly reduced final BW, ADG, and ADFI ( < 0.01) and reduced efficiencies of ADF and
ether extract utilization ( = 0.05 and = 0.02, respectively) regardless of vaccination status. No significant treatment effects were found on
manure output,
manure pH, efficiencies of
lignin utilization, and N retention. Infecting pigs with PRRSV increased daily
manure CO emission per pig ( = 0.01). There was an interaction between immunization and
infection for NO per pig with
manure from uninfected, vaccinated pigs producing as much as the
manure from infected, vaccinated pigs whereas there was a difference by PRRSV
infection state for nonvaccinated pigs. There were also interactions between treatments for HS and NO emissions per kilogram of
manure volatile solids excreted ( = 0.01 and = 0.0001, respectively) with the same pattern as for NO per pig; that is, the vaccinated pigs had similar rates of emission regardless of
infection state. Pigs infected with PRRSV increased NO
nitrogen per kilogram of total N excreted compared with noninfected groups ( = 0.03). Collectively, these results indicated that PRRSV
infection caused decreased growth rates and nutrient utilization efficiency and increased gas emissions from stored
manure.