The purpose of this study was to evaluate the effect of pGRF gene plasmid on growth performance and immunological function of immune-challenged weaned piglets,and also the potential mechanism of these effects were discussed.Eighteen weaned piglets(Duroc×Landrace×Large White) with ages of(35±2)d and initial body weight(BW)(7.86±0.59)kg were not castrated and randomly assigned into three treatments according to gender and BW by single factor design.Three treatments were pGRF gene plasmid group,pGRF gene plasm...