Thursday, July 20, 2017

Effect of immunologic solutions on sows and gilts on time-to-stability, and on production losses in breeding herds infected with 1-7-4 PRRS virus

 2017 Sep 1;144:112-116. doi: 10.1016/j.prevetmed.2017.05.024. Epub 2017 Jun 6.

Effect of immunologic solutions on sows and gilts on time to stability, and production losses in breeding herds infected with 1-7-4 PRRSv.

Author information

1
Iowa State University College of Veterinary Medicine, 2221 Lloyd Veterinary Medicine Center, 1600 16S Street, Ames, IA, 50010, USA. Electronic address: dcl.linhares@gmail.com.
2
University of Minnesota College of Veterinary Medicine, 385B Animal Science Veterinary Medicine Building, 1988 Fitch Avenue, St. Paul, MN, 55108, USA.

Abstract

Porcine reproductive and respiratory syndrome virus (PRRSv) is an economically significant swine pathogen causing production losses in the global swine industry. Clinical impact depends on many factors including the virus itself. One method to sub-type PRRSv is using restriction fragment length polymorphism (RFLP). The RFLP pattern 1-7-4 emerged within the United States swine industry in 2014 and has become prevalent since then. This was a field study that prospectively followed 1-7-4-infected breeding herds (n=107) and compared time to stability (TTS), time to baseline production (TTBP) and total loss per 1000 sows between herds using modified-live virus vaccine (MLV) on sows and gilts (MLV-MLV), MLV on sows and MLV in addition to field virus exposure on gilts (MLV-MLV/FVE) or not deliberately exposing sows or gilts to PRRSv (Natural-Natural). Analyses were done in SAS 9.4 and results were adjusted by selected co-variates (duration of herd closure, number of previous PRRSv outbreaks of last 3 years, weaning frequency/week, gilt development unit location, herd size and production system). Survival analysis was conducted on TTS and TTBP and regression analysis on total loss. Herds in the Natural-Natural group achieved TTS and TTBP before other herds. Herds in the MLV-MLV/FVE had the longest TTS and TTBP. The total loss was numerically least in MLV-MLV herds (1194 pigs/1000 sows) compared to MLV/MLV-FVE (1810/1000 sows) and Natural-Natural (2671/1000 sows). This study provided additional information to assist veterinarians deciding between methods of exposure to manage PRRSv infection from breeding herds.

KEYWORDS: 

Control; EWMA; Elimination; Live virus exposure; Modified-live virus vaccine; PRRSv; Pigs; Statistical process control; Whole herd exposure
PMID:
 
28716191
 
DOI:
 
10.1016/j.prevetmed.2017.05.024

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