Effect of oxidized soybean oil on the immune response to porcine reproductive and respiratory syndrome modified live virus vaccine in nursery pigs

Abstract

This study evaluated the effect of oxidized soybean oil on the immune response to porcine reproductive and
respiratory syndrome modified live vaccine (PRRS-MLV), and the oxidative stress status in nursery pigs. Seventy
castrated weaned pigs, from a free PRRS virus infected herd, were divided into two groups: treatment group (n=63)
and control group (n=7). The treatment pigs were vaccinated with the PRRS-MLV and then divided into three groups
based on different diet types containing different soybean oils: (A) 5% fresh oil, (B) 5% heated oil for 43 h, and (C) 5%
heated oil for 38 h. The control pigs were not vaccinated and consumed (A) diet. Blood samples were collected for PRRS
immune response and for measuring oxidative status. No significant differences were observed among groups in
malondialdehyde (MDA), superoxide dismutase-1 (SOD-1), ELISA titer, and SN antibodies against PRRS virus.
Notably, the percentage of interferon-gamma (IFN-) producing cell increased significantly in group A in comparison
to that in the other groups on D28 and D56. In contrast, the percentage of interleukin-10 (IL-10) producing cell was
highest in group C, followed by group B and group A, respectively. Moreover, group C exhibited a higher number of
IL-10 producing cells compared to group A on D56 (p=0.082). Oxidized soybean oil exerts a negative effect on the cellmediated immune response to PRRS-MLV, especially in pigs fed oil containing high peroxide value and high numbers
of total polar compounds. These findings suggest that pig farmers should be more concerned with the quality of oil
used in the diet for nursery pigs.