Open Access
Research (Published online: 24-08-2023)
16. Effectiveness of gilt acclimatization - improvement procedures in a farm with recurrent outbreaks of porcine epidemic diarrhea
Pimpakarn Suwan, Alongkot Boonsoongnern, Sahathat Phuttapatimok, Manakorn Sukmak, Pichai Jirawattanapong, Wilairat Chumsing, Orawan Boodde, Krithiran Woramahatthanon, and Yonlayong Woonwong
Veterinary World, 16(8): 1695-1701

Pimpakarn Suwan: Graduate Program in Veterinary Clinical Studies, Faculty of Veterinary Medicine, Kasetsart University, Kamphaeng Saen, Nakhon Pathom, 73140, Thailand.
Alongkot Boonsoongnern: Department of Farm Resources and Production Medicine, Faculty of Veterinary Medicine, Kasetsart University, Kamphaeng Saen, Nakhon Pathom, 73140, Thailand.
Sahathat Phuttapatimok: Kamphaengsaen Veterinary Diagnostic Center, Faculty of Veterinary Medicine, Kasetsart University, Kamphaeng Saen, Nakhon Pathom, 73140, Thailand.
Manakorn Sukmak: Department of Farm Resources and Production Medicine, Faculty of Veterinary Medicine, Kasetsart University, Kamphaeng Saen, Nakhon Pathom, 73140, Thailand.
Pichai Jirawattanapong: Department of Farm Resources and Production Medicine, Faculty of Veterinary Medicine, Kasetsart University, Kamphaeng Saen, Nakhon Pathom, 73140, Thailand.
Wilairat Chumsing: Department of Farm Resources and Production Medicine, Faculty of Veterinary Medicine, Kasetsart University, Kamphaeng Saen, Nakhon Pathom, 73140, Thailand.
Orawan Boodde: Department of Farm Resources and Production Medicine, Faculty of Veterinary Medicine, Kasetsart University, Kamphaeng Saen, Nakhon Pathom, 73140, Thailand.
Krithiran Woramahatthanon: Kamphaengsaen Veterinary Diagnostic Center, Faculty of Veterinary Medicine, Kasetsart University, Kamphaeng Saen, Nakhon Pathom, 73140, Thailand.
Yonlayong Woonwong: Department of Farm Resources and Production Medicine, Faculty of Veterinary Medicine, Kasetsart University, Kamphaeng Saen, Nakhon Pathom, 73140, Thailand.

doi: 10.14202/vetworld.2023.1695-1701

Article history: Received: 10-04-2023, Accepted: 18-07-2023, Published online: 24-08-2023

Corresponding author: Yonlayong Woonwong

E-mail: yonlayong.w@ku.th

Citation: Suwan P, Boonsoongnern A, Phuttapatimok S, Sukmak M, Jirawattanapong P, Chumsing W, Boodde O, Woramahatthanon K, and Woonwong Y (2023) Effectiveness of gilt acclimatization - improvement procedures in a farm with recurrent outbreaks of porcine epidemic diarrhea, Veterinary World, 16(8): 1695-1701.
Abstract

Background and Aim: Porcine epidemic diarrhea (PED) is a severe infectious disease that causes very high mortality in newborn piglets up to 2-3 weeks age. The main cause of repeated outbreaks of PED in infected farms is the continuing circulation of the PED virus (PEDV). Improper gilt management, including inappropriate gut feedback, commingling, and inadequate immunization, causes a prolonged virus circulation in breeding herds. Moreover, insufficient transfer of passive immunity through the colostrum to newborn piglets can also increase infection risk. Therefore, a gilt management program that controls infection should focus on infection monitoring and acclimatization. We investigated the source of recurrent PEDV outbreaks and examined how the effect of immunization methods, specifically using gut feedback mechanism and vaccination, can reduce PEDV circulation and improve immune responses in replacement gilts.

Materials and Methods: The study site was a segregated commercial production farm with endemic PEDV. The acclimatization methods included gut feedback and vaccination. This longitudinal study evaluated two strategies of gilt acclimatization against PEDV: Program 1 (routine farm management) and Program 2 (early feedback program and all-in-all-out system). Levels of PED RNA in fecal samples were measured using quantitative reverse transcription-polymerase chain reaction, and the PEDV S gene was sequenced. Porcine epidemic diarrhea-specific immune responses were assessed using enzyme-linked immunosorbent assay and the serum neutralization test.

Results: Porcine epidemic diarrhea outbreaks occurred in the farrowing, nursery, and finishing units and farrowed litters 5–10 days old were symptomatic of PED. Phylogenetic analyses of the S gene showed PEDV sequence divergence between PEDV field strains and vaccine strain, which may contribute to periodic outbreaks and continued persistence of PEDV in the farm. After gut feedback and acclimatization, replacement gilts from Program 1 continued to shed PEDV before being introduced to sow herds, while those from Program 2 did not shed PEDV before being introduced to sow herds. However, the components of the immune response against PEDV in serum samples, including specific immunoglobulin (Ig)G, specific IgA, and neutralizing antibodies were lower in gilts of Program 2 than those in Program 1.

Conclusion: We speculate that implementing the appropriate gilt acclimatization program can control PEDV circulation in farm. However, the acclimatization methods in Program 2 did not induce a strong and adequate immune response in replacement gilts. Therefore, maternal immunity levels and the degree of protection against PEDV require further study.

Keywords: acclimatization, gilt, immune response, phylogenetic tree, porcine epidemic diarrhea.