Effect Of Selenium-Rich Yeast On LPS-Induced Immune-Stressed Early Weaned Piglets

An immunologically stressed pig model was established by intramuscular injection with E.coli lipopolysaccharide(LPS) to evaluate the effects of dietary selenium-rich yeast(SeY) on the growth performance,immune function,and antioxidant status under the immunological challenge.Twenty five Meishan weanling pigs[28(s.d.2 d)]were randomly assigned to five treatments according to gender and weight by single factor design.The Five treatments were selenium-rich yeast group (SeY),sodium selenite group(SSe),selenium-rich yeast+LPS group(SeY+LPS), sodium selenite+LPS group(SSe+LPS),sodium selenite+Yest+LPS group(SSe +Y+LPS),each treatment had five replicates,each replicate has one piglet.All dietary treatments supplemented with 0.3 mg Se/kg and no additive antibiotics. During the 28 days experiment the piglets were allowed ad libitum to feed and water. On d 14 and d 21,half of pigs in each dietary treatment were intramuscularly injected with either 50μg/kg BW LPS or an equivalent amount of sterile saline.Blood samples were collected for analyzing the concentrations of serum interleukin-1β(IL-1β),interleukin-6(IL-6) insulin like growth factor(IGF-1),ImmunoglobulinA,G,M (IgA,G,M) and malonaldehyde(MDA),and the activities of glutathione peroxidase (GPX) and superoxide dismutase(SOD) at 3 h post-injection.Average daily feed intake(ADFI),average daily gain(ADG),feed to gain ratio(F/G) were recorded.The results were as follows:1) Diet supplemented with SeY relieved the decrease in ADG(d 14-21 and d 21-28,P＜0.05)of Meishan piglets immunologically stressed by LPS,and improved feed utilization ratio(d 21-28,P＜0.05) compared with SSe supplemented treatments. 2) Diet supplemented with SeY inhibited the LPS-induced increase of the serumal IL-1βand IL-6(d14 and d 21,P＜0.01) levels and the decrease of the serumal IGFI(d 21,P＜0.05),IgG(d 21,P＜0.05) and IgM(d14 and d 21,P＜0.01) contents compared with SSe supplemented treatments.The concentration of serum IgM in the SSe+Y+LPS group was lower(P＜0.01) than that in the SeY+LPS group but higher(P＜0.01) than that in the SSe+LPS group at d 21.3) Diet supplemented with SeY relieved the LPS-induced decrease of GPX and SOD activities,and the increase of MDA level in sera compared with SSe supplemented treatments.In conclusion,SeY could relieve the adverse effects of immunological stress on growth performance of the Meishan piglets which were injected with lipopolysaccharide,and could inhibit increase of the serumal IL-1βand IL-6 levels and decrease of the serumal IGF-I contents of immunological stress piglets,which may result from that SeY enhanced the activities of GPX and SOD and decreased the level of MDA in sera,improved the body antioxidant capacity under the immunological Stressed.