Impact of porcine epidemic diarrhea on performance of growing pigs

Abstract

The impact of porcine epidemic diarrhea virus (PEDv) infection on the US pork industry has mainly been attributed to the mortality that it causes in suckling piglets, and, consequently, much effort has been invested in the quantification of its effect in sow farms. However, no information on the performance of surviving pigs that were exposed to the PEDv as piglets is available. Here, a retrospective cohort study to evaluate the impact of porcine epidemic diarrhea virus (PEDv) infection on growing pigs' performance, as indicated by mortality, average daily gain (ADG), average daily feed intake (ADFI), and feed conversion ratio (FCR) was performed using production records from weaned pigs in nursery and wean-to-finish sites from sow farms that became PEDv-infected between May 2013 and June 2014. Production records from the first batch of growing pigs weaned in infected flows after the PEDv outbreak ("infected batches") were compared with those from pigs weaned within the previous 14 to 120 days ("control batches"). Performance records from infected and control batches, paired by flow, were compared using non-parametric paired tests. Mortality, ADG and FCR were significantly different in PEDv-positive (infected) compared with PEDv-negative (control) batches, with a mean increase of mortality and FCR of 11% and 0.5, respectively, and a decrease of ADG of 0.16 lb/day. Our results demonstrate a poorer performance of growing pigs weaned after a PEDv outbreak compared with those weaned within the previous 14-120 days, suggesting that in addition to the mortality induced by PEDv in suckling pigs, the disease also impairs the performance of surviving pig. These findings help to quantify the impact of PEDv infection in the US and, ultimately, contribute to efforts to quantify the cost-effectiveness of disease prevention and control measures.

Fig 1. Feed conversion rate (FCR) and mortality in nursery and wean-to-finish batches in the 4 months before Porcine Epidemic Diarrhea detection in 18 flows and in the first batches weaned after the outbreak.

Fig 2. Mortality observed in paired batches from 18 flows in the first batch produced after PED detection in the sow farms (infected batches) and in the immediate previous batch (produced within the previous four months, control batches).

Dotted line: no differences in mortality.

Fig 3. Average daily gain (ADG, Fig. 3a) and feed conversion ratio (FCR, Fig. 3b) observed in paired batches from 18 flows in the first batch produced after PED detection in the sow farms (infected batches) and in the immediate previous batch (produced within the previous four months, control batches).

Dotted line: no differences in ADG/FCR.