Impact of Porcine Epidemic Diarrhea on Performance of Growing Pigs

<div><p>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.</p></div

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).

<p>Dotted line: no differences in ADG/FCR.</p

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.

<p>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.</p

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).

<p>Dotted line: no differences in mortality.</p

Univariate logistic regression analysis to evaluate association between independent variables and PRRS incidence between July 2012 and June 2014 in the RCP-N212.

<p>Univariate logistic regression analysis to evaluate association between independent variables and PRRS incidence between July 2012 and June 2014 in the RCP-N212.</p

Observed (grey lines) and predicted (black lines) probably of sharing PRRS-status from July 2012 to June 2014.

<p>Continuous and dotted lines correspond to sharing PRRS-status for SS and NSS enrolled in the RCP-N212 respectively. Months from July 2012 to June 2014 are represented from 1 to 24.</p

Results of the most parsimonious mixed-effects logistic model fitted to evaluate trends of active report of PRRS status from July 2012 to June 2014 in the RCP-N212.

<p>Results of the most parsimonious mixed-effects logistic model fitted to evaluate trends of active report of PRRS status from July 2012 to June 2014 in the RCP-N212.</p

Results of the most parsimonious mixed-effects logistic model fitted to evaluate monthly trend of PRRS incidence between July 2012 and June 2014 in the RCP- N212.

<p>Results of the most parsimonious mixed-effects logistic model fitted to evaluate monthly trend of PRRS incidence between July 2012 and June 2014 in the RCP- N212.</p

Total producing swine premises within counties in the RCP-N212 area, disaggregated into SSs and NSSs that were enrolled (E).

<p>Among E, number of premises that shared PRRS status (Sh), and number of incident cases of PRRS (1) from Sh.</p

Perspective plot of space-time pair correlation function for PRRS incident cases from July 2012 to June 2014 in the RCP-N212.

<p>Time (in weeks, from 0-wk to 104-wks) is represented by axis <i>v</i>; while space (in km, from 0-km to 6-km) is represented by axis <i>u</i>. Vertical axis represents the space and time correlation.</p