PSIII-9 Effect of maternal immune activation during gestation on piglets’ cortisol response to stress

Maternal immune activation (MIA) during gestation can affect the ability of the offspring to cope with stress such as weaning. Cortisol, a glucocorticoid released in response to stress, is an established indicator of stress. The purpose of this study was to evaluate the cortisol response to weaning stress of offspring exposed to MIA during gestation. Camborough gilts were inseminated at approximately 235 days of age. On gestational day 76, gilts (n = 11) were inoculated with porcine reproductive and respiratory syndrome virus (PRRSV) intranasally whereas saline was intranasally administered to Control gilts (n = 7). On postnatal day (PD) 21 approximately half of the male and female piglets remained with sows (suckled) while the rest were weaned. Blood was collected from the piglets prior to weaning on PD21 and at PD22. ELISA was used to measure cortisol in the serum. The analysis of cortisol concentration tested for the fixed effects of gilt treatment (PRRSV or Control), piglet sex (female or male), management (suckled or weaned), day of sampling (PD21 or PD22), interactions, and for Normality assumptions. At PD22 female weaned piglets had a higher level of cortisol when compared to female suckled piglets in both Control (P < 0.05) and PRRSV (P < 0.05). Males exhibited a similar trend that did not reach significance. Cortisol concentrations were lower in male piglets from Control relative to PRRSV-treated gilts and the differences were more pronounced among the suckled group. The results suggest that MIA elevates basal serum cortisol in unstressed males. This study is supported by USDA NIFA AFRI, 2018-67015-27413.