Effects ofporcine reproductive and respiratory syndrome virus on pig growth, dietutilization efficiency, and gas release from stored manure
M. M. Li, K.M. Seelenbinder, M. A. Ponder, L. Deng, R. P. Rhoads, K. D. Pelzer, J. S.Radcliffe, C. V. Maxwell, J. A. Ogejo and M. D. Hanigan
The objectivesof this study were to examine the effects of porcine reproductive andrespiratory syndrome virus (PRRSV) infection and vaccination on pig growth,dietary nutrient efficiency of utilization, manure output, and emissions ofCO2, CH4, H2S, N2O, and NH3 gases from stored manure. Forty-eight pigs, aged 21d at the start of the study, were subjected to 1 of 4 treatment combinationsarranged in a 2 × 2 factorial design with main factors of PRRSV vaccination andPRRSV infection. Body weight, ADFI, manure output, and nutrient efficiency ofutilization were assessed and gas emissions from stored manure were determineddaily 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 (P < 0.01) andreduced efficiencies of ADF and ether extract utilization (P = 0.05 and P =0.02, respectively) regardless of vaccination status. No significant treatmenteffects were found on manure output, manure pH, efficiencies of ligninutilization, and N retention. Infecting pigs with PRRSV increased daily manureCO2 emission per pig (P = 0.01). There was an interaction between immunizationand infection for N2O per pig with manure from uninfected, vaccinated pigsproducing as much as the manure from infected, vaccinated pigs whereas therewas a difference by PRRSV infection state for nonvaccinated pigs. There werealso interactions between treatments for H2S and N2O emissions per kilogram ofmanure volatile solids excreted (P = 0.01 and P = 0.0001, respectively) withthe same pattern as for N2O per pig; that is, the vaccinated pigs had similarrates of emission regardless of infection state. Pigs infected with PRRSVincreased N2O nitrogen per kilogram of total N excreted compared withnoninfected groups (P = 0.03). Collectively, these results indicated that PRRSVinfection caused decreased growth rates and nutrient utilization efficiency andincreased gas emissions from stored manure。