Probiotic bacterium Lactobacillus rhamnosus GG (LGG) has been demonstrated to adhere to pig intestinal mucus, and is able to displace and inhibit pathogens, including Escherichia coli (E. coli), in vitro. However, currently there are few data concerning the effects of LGG on piglet health. The objectives of this study were to assess the effectiveness of LGG in reducing the incidence and severity of post-weaning diarrhoea in piglets, and to investigate its mechanisms of action. Eighteen weaned barrows were allocated to nonchallenged control (NCN), challenged control (CCN) and LGG treatment (LGG) groups. Diarrhoea incidence was significantly lower in group LGG than group CCN after E. coli challenge. Faecal coliform bacteria counts were significantly increased, while lactobacilli and bifidobacteria counts were decreased, in group CCN compared with the other groups after challenge. In the jejunum and ileum, secretory immunoglobin A (SIgA) concentrations were significantly higher in group LGG than in group CCN. In group LGG, administration of short-term LGG before E. coli infection attenuated the elevation of serum IL-6 induced by E. coli. Significantly higher concentrations of TNF-alpha were observed in group LGG than NCN and CCN at 6h. IL-1beta concentrations in group NCN were significantly higher than LGG at 6h and higher than CCN at 24h. In conclusion, LGG was effective in ameliorating diarrhoea in post-weaning piglets induced by E. coli K88, possibly via modulation of intestinal microflora, enhancement of intestinal antibody defence, and regulation of production of systemic inflammatory cytokines.
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