Stimbiotics supplementation promotes growth performance by improving plasma immunoglobulin and IGF-1 levels and regulating gut microbiota composition in weaned piglets

This study was conducted to investigate the effects of dietary supplementation with 19stimbiotics (STB) on growth performance, diarrhoea incidence, plasma antioxidant capacity, im- 20munoglobulin concentration and hormone levels, and faecal microorganisms in weaned piglets. 21Compared with the control group, the addition of STB improved BW of piglets on days 28 and 42 22(P < 0.05) and increased daily weight gain and daily feed intake from days 14-28 and throughout 23the trial period (P < 0.05). Correspondingly, plasma insulin-like growth factor 1 (IGF-1) level on day 2442 was significantly improved by STB (P < 0.05). VP group levels of immunoglobulin (Ig) A and G 25were significantly higher on days 14 and 42 (P < 0.05) than CT group levels. And the activity of 26plasma catalase tended to be increased on day 14 (P = 0.053) in the VP group, as for superoxide 27dismutase, glutathione peroxidase and malondialdehyde, STB did not significantly affect their 28levels (P > 0.05). Moreover, dietary STB increased the relative abundance of beneficial bacteria, 29including norank_f_Muribaculaceae, Rikenellaceae_RC9_gut_group, Parabacteroides, and unclassi- 30fied_f__Oscillospiraceae. In summary, STB improved the immunity and IGF-1 levels in the plasma of 31weaned piglets as well as regulated the microbial community in the faeces, and consequently 32promoted the growth performance of weaned piglets.