Effect of two porcine epidemic diarrhea (PED) vaccines on prewean mortality under field conditions in Mexico

The main impact of Porcine Epidemic diarrhea (PED) virus is high mortality in piglets between birth and weaning and as a consequence pig producers have serious economic losses. Since 2014, Mexico has been positive to PED virus as diagnosed by the PCR test.

The aim of this study was to assess the effect of two vaccines against PED (manufactured by ZoetisTM and Harrisvaccines^TM respectively) compared to no vaccination. During a multi-site outbreak that occurred in March, 2015, the vaccines were applied in sows and gilts and unvaccinated controls were also kept. Both PED vaccines were used according to their label directions (intramuscular injection, pre-farrowing). Diagnostic testing revealed that some sites were affected by the prototype PED virus and others with the Indel strain. Response variables, measured on a per litter basis, were: total pigs born, pigs born alive, mummies, stillborn, pigs weaned pigs, dead pigs and mortality rate. The data were analysed by means of a mixed linear model including the random effects of farm and farrowing group and the fixed effects of parity (1 or greater than 1), vaccine strain (HarrisvaccinesTM and ZoetisTM) & challenge strain (Prototype or Indel). 31492 records were included in the data base.

All vaccinated groups showing low premortality weaning and better piglet quality. Gilts (1st farrow) yielded smaller litters and had higher mortality rates (12.4 vs 13.4 and 47.5 vs 38.0% respectively, P< 0.01) than sows (2nd farrow or greater). Animals in the control group had more deaths per litter than those treated with either vaccine (7.8, 3.0 and 2.8 for control, Zoetis and HarrisvaccinesTM, respectively. P< 0.05) and higher prewean mortality rate (65.4, 24.4 and 24.9 for control, Zoetis and Harris vaccines^TM, respectively. P< 0.05). Differences between challenge strains were found for pigs weaned, number of deaths and mortality rate per litter (9.1 vs 6.7; 3.1 vs 5.0 and 25.8 vs 42.3 for Indel and Prototype strains), although these differences could also have been influenced by site factors.

The use of either PED vaccine reduced prewean mortality independently of challenge strain (Indel or Prototype viruses). PED vaccines can help to reduce negative impact of PED disease in infected herds. The use of the vaccines are an excellent tools to control the disease in addition to biosecurity measures.

Disclosure of Interest: None Declared.