Impact of porcine epidemic diarrhea on herd and individual Berkshire sow productivity

Transcriptomics yields valuable information regarding the response mechanisms of Chinese Min pigs infected with PEDV

Porcine epidemic diarrhea virus (PEDV) causes porcine epidemic diarrhea (PED), a highly infectious disease, which has resulted in huge economic losses for the pig industry. To date, the pathogenic and immune response mechanism was not particularly clear. The purpose of this study was to investigate the pathogenic and immune responses of pigs infected with PEDV.In this study, 12 Min pigs were randomly selected without taking colostrum. At 3 days old, eight piglets were infected with 1 mL of PEDV solution (10 TCID50/ml), and the remaining four piglets were handled by 1 mL of 0.9% normal saline. Within the age of 7 days old, four piglets died and were considered as the death group. Correspondingly, four alive individuals were classified into the resistance group. Tissues of the duodenum, jejunum, ileum, colon, cecum, and rectum of piglets in the three groups were collected to measure the PEDV content. Additionally, the jejunum was used for the measurements and analyses of Hematoxylin-eosinstaining (HE), immunohistochemical sections, and transcriptomics. The phenotypes of Min piglets infected with PEDV showed that the viral copy numbers and jejunal damage had significant differences between the death and resistance groups. We also observed the transcriptome of the jejunum, and the differentially expressed (DE) analysis observed 6,585 DE protein-coding genes (PCGs), 3,188 DE long non-coding RNAs (lncRNAs), and 350 DE microRNAs (miRNAs), which were mainly involved in immune response and metabolic pathways. Furthermore, the specific expressed molecules for each group were identified, and 97 PCGs,108 lncRNAs, and 51 miRNAs were included in the ceRNA-regulated networks. By weighted gene co-expression network analysis (WGCNA) and transcription factor (TF) prediction, 27 significant modules and 32 significant motifs (E-value < 0.05) annotated with 519 TFs were detected. Of these TFs, 53 were DE PCGs. In summary, the promising key PCGs, lncRNAs, and miRNAs related to the pathogenic and immunological response of pigs infected with PEDV were detected and provided new insights into the pathogenesis of PEDV.

Assessment of abortion risk of sows on Japanese commercial farms infected with porcine epidemic diarrhea virus

The objectives of this study were to assess abortion risk (AR) and the number of piglets that died during suckling periods per litter (DP) in farms infected with porcine epidemic diarrhea (PED) in relation to herd immunization procedures. Data were obtained from 91 farms in Japan that had PED infection during 2013 to 2014. The 91 PED-positive farms were asked the number of abortions that occurred and DP for 3 months (1 month before PED outbreak (previous month), 1 month after PED outbreak (the month of PED), and from 1 month after PED outbreak to 2 months after PED outbreak (following month)). AR in each month was calculated as the number of abortions divided by sow inventory. Both AR and DP in the month of PED were higher than those in the previous and following months (p < .05). Farms that performed a herd immunization procedure had higher AR and DP in the month of PED than those that did not perform the procedure (p < .05). In summary, PED occurrence increased AR and DP.

Development of a biosecurity assessment tool and the assessment of biosecurity levels by this tool on Japanese commercial swine farms

It is well known that infectious diseases such as porcine reproductive and respiratory syndrome (PRRS) and porcine epidemic diarrhea (PED) decrease herd productivity and lead to economic loss. It is believed that biosecurity practices are effective for the prevention and control of such infectious diseases. Therefore, the objective of the present study was to investigate whether or not an association between biosecurity level and herd productivity, as well as disease status exists on Japanese commercial swine farms. The present study was conducted on 141 farms. Biosecurity in each farm was assessed by a biosecurity assessment tool named BioAsseT. BioAsseT has a full score of 100 and consists of three sections (external biosecurity, internal biosecurity and diagnostic monitoring). Production data for number of pigs weaned per sow per year (PWSY) and post-weaning mortality per year (PWM) were collected for data analysis. Regarding PRRS status, the farms were categorized into two groups: unknown or unstable and stable or negative. In addition, these farms were categorized based on their PED status, either positive or negative. The total BioAsseT score was associated with herd productivity: as total score increased by 1, PWSY increased by 0.104 pigs and PWM decreased by 0.051 % (P <  0.05). Herd productivity was associated with the score of external and internal biosecurity (P <  0.05), but did not correlate with the score of diagnostic monitoring. Regarding PRRS status, farms with an unknown or unstable status had lower total score than those with stable or negative status (P < 0.05). Similarly, PED positive farms had a lower total score compared to PED negative farms (P <  0.05). In conclusion, the present study provides evidence for the association between high biosecurity levels and increased herd productivity as well as a decreased risk for novel introductions of infectious diseases such as PED.

Effect of intervention practices to control the porcine epidemic diarrhea (PED) outbreak during the first epidemic year (2013-2014) on time to absence of clinical signs and the number of dead piglets per sow in Japan

Porcine epidemic diarrhea (PED) is an emerging and/or re-emerging disease of pigs in several countries, with high morbidity and mortality in suckling piglets. Farms affected with PED perform various intervention practices to control and/or eliminate the PED virus. The objectives of the present study were to assess the effect of biosecurity measures and intervention practices to control PED on time to absence of clinical signs (TAC) and number of dead suckling piglets during TAC. A questionnaire was administered to 120-PED affected farms located across Japan between 2013, when the first case was reported in Japan, and 2014. Farms were asked to provide information on farm characteristics and internal or external biosecurity measures during PED outbreak, as well as on intervention practices to control PED. The TAC was defined as the number of days from the date that clinical PED signs appeared to the date that clinical PED signs disappeared. The number of dead piglets per sow (DP/S) was calculated as the number of dead suckling piglets during TAC divided by the sow inventory. Regarding the effect of biosecurity measures during PED outbreak on TAC and DP/S, longer TAC was observed in Actinobacillus pleuropneumoniae-positive farms and farms outsourcing pig transport to the slaughterhouse (p <  0.05). In addition, farms with divided truck entrances had lower DP/S than those without divided entrances (p <  0.05).Regarding the effect of intervention practices to control PED on TAC and DP/S, farms that performed feedback at 2 weeks or later after PED outbreak had longer TAC and higher DP/S than other farms (p <  0.05). Farms that fixed the hours staff worked in farrowing barn had lower DP/S than the other farms (p <  0.05). In conclusion, variables associated with long TAC were Actinobacillus pleuropneumoniae -positive farms, farms outsourcing pig transport to the slaughterhouse, and farms performing feedback at 2 week or later after PED outbreak. Additionally, those associated with high DP/S were farms without divided entrances, farms without a fixed hours worked in the barn, and farms that performed feedback at 2 week or later after PED outbreak.

Assessment of reproductive performance in F1 sows exposed to the porcine epidemic diarrhea virus at different periods of production stage on farms with different hygienic environments

Porcine epidemic diarrhea (PED) occurred in Japan in 2013 after an interval of 7 years. The present study assessed individual productivity of sows exposed to PED virus at different periods of the production stage. The present study was performed at three commercial farms that had PED outbreak during the month of December 2013. Herd immunization was conducted for all gilts and sows. The production records were obtained for sows that were alive during the PED outbreak at each farm. The sows were categorized into six groups based on the period in which they were exposed to PED virus between days 0-30 (G1), 31-60 (G2), 61-90 (G3), or after 91 days of pregnancy (G4), during lactation (L), and after weaning (W). The control group was assigned based on the records before the period of PED outbreak (uninfected group). The number of sow's records obtained from farms A, B, and C were 1056, 1137, and 1035, respectively. Compared with the uninfected group, there was no reduction in the number of pigs born alive in the G1-G4 groups. Sows of the G4 and L groups, however, had 4-9 pigs fewer pigs weaned, and a 36%-77% greater pre-weaning mortality than the uninfected group (P < 0.05). There was no difference in farrowing rate and number of pigs born alive at subsequent parities among the sow groups. There were no interactions between sow groups and parity for sow productivity.