| The objectives of present study aims to grasp systematically the effects of diets added with 1.2%,0.8%,0.5% OPS on growth performance and immunity of weanling piglets after immunological stress induced by LPS, to reveal the mechanism of OPS on growth and immunity, to explore whether it could be a feasibility means of anti-stress, to choose the appropriate addition based on data, and to provide theoretical basis for exploiting OPS as a green feed additive.To study the effects of OPS on growth performance and IGF-1 in weaning piglets after immunological stress induced by LPS. IGF-1 concentrations in the serum were measured by ELISA, IGF-1 mRNA level in the intestines were measured by Real-time PCR. The results showed that ADG between each group have no significant differences (P>0.05), the rank of mean value was E>D>C>A/B and compared with group A/B, the value of group C, D and E were improved 2.27%,9.82%,16.12%; F/G mean value of each group was A/B>C>D>E. The effect has a tendency to increase along with the OPS amount. IGF-1 level and IGF-1 mRNA level in piglets fed 0.5%,0.8%,1.2% OPS were extremely significant higher than that in the immunological stress control group (P<0.01). These results indicate that dietary supplementation of OPS could improve growth performance and alleviate the immunological stress caused by LPS, and the effect of remission is better when piglets fed basal diet supplemented with 0.8% OPS.To reveal the effects of OPS on disaccharide enzyme activity in the duodenum, jejunum and ileum of weaning piglets after immunological stress induced by LPS. The disaccharide enzyme activities were measured by disaccharide enzyme kit. The results showed that dietary supplementation of OPS was able to improve the disaccharide enzyme activity and alleviated the immunological stress caused by LPS. The effect of remission is better when piglets fed basal diet supplemented with 0.8% OPS.To investigate the effects of OPS on intestinal mucosal mechanical barrier, the villus height, width, crypt depth and the radio of villous height and crypt in duodenum, jejunum and ileum were detected by light microscope, tight junction protein Occludin, ZO-1 and Claudin-1 mRNA expressions in duodenum, jejunum and ileum were detected by Real-time PCR. The results showed that: ①LPS could make the villus crypt depth deeper, but dietary supplementation of 1.2%,0.8%,0.5% OPS could increase the villus height in duodenum, jejunum and ileum (P<0.05), make crypt depth more shallow and increase the villus height/crypt depth values. ② Immunological stress induced by LPS could reduce Occludin, ZO-1 and Claudin-1 mRNA expression (P<0.01) and increase intestinal permeability. OPS could increase the expression above three. Diet supplemented with 0.8% OPS could significantly improve Occludin, ZO-1 and Claudin-1 mRNA expression, decrease intestinal permeability, maintain intestinal structure and increase tight junction. However, Occludin and ZO-1 mRNA expressions were zero or almost zero when diet supplemented with 0.5% OPS. The results indicate that:dietary supplementation of 1.2%,0.8%,0.5% OPS could increase the intestinal mucosal barrier function under the immunological stress, possibly by improving the intestinal mucosal villous structure and improving the role of tight junctions, and the effect of remission is better when piglets fed basal diet supplemented with 0.8% OPS.To explore the effect and mechanism of OPS on intestinal mucosal immunologic barrier, IL-1β, IL-6, IL-12 and TNF-a concentrations in the serum were measured by ELISA, IL-1β, IL-6, TNF-a and TLR-4 mRNA expression in the jejunal mucosa were detected by Real-time PCR. The results showed that: ①IL-1β,IL-6, IL-12 and TNF-a concentrations in the serum in groups with diet supplemented with OPS were lower than group B, and were not significantly different from group A (P>0.05), which prompted that OPS could inhibit inflammatory cytokines IL-1β, IL-6 and TNF-a secretion induced by LPS, and protected the weaning piglet from the immunity stress. ② Dietary supplementation of 0.8% and 0.5% OPS could significantly decrease IL-1β, IL-6, TNF-a and TLR-4 mRNA expression in jejunal mucosa of weaning piglets. Inflammatory cytokines expression with dietary supplementation of 0.5% OPS significantly lower than group A. Dietary supplementation of 1.2% OPS have no effect on inflammatory cytokines expression in immunological stress induced by LPS. The results show indicate that:Dietary supplementation of 1.2%,0.8%,0.5% OPS could increase the intestinal mucosal immune barrier by acting on the intestinal mucosal immune effector molecules, and the effect of remission is better when piglets fed basal diet supplemented with 0.8% OPS. |
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