Effects of Actigen, a second-generation mannan rich fraction, in antibiotics-free diets on growth performance, intestinal barrier functions and inflammation in weaned piglets

Abstract

This study aimed to investigate the effects of Actigen™, a second-generation mannan rich fraction, on growth performance, intestinal morphology and permeability, and intestinal inflammatory response in weaned piglets. A total of 150 healthy weaned piglets were randomly assigned to the Control, Antibiotics and Actigen groups and received 1 of 3 dietary treatments: a basal antibiotics-free diet to which 250 mg/kg antibiotics (100 mg/kg colistin sulfate, 100 mg/kg olaquindox, and 50 mg/kg Kitasamycin) or 800 mg/kg Actigen were added. Body weight and feed intake were recorded. On day 28 of experimentation, five female and five male piglets per treatment were selected to collect blood, small intestinal segments and mucosa samples. Intestinal morphology and goblet cell number were determined. Expression of tight junction proteins and TLR4 signaling were detected. d-lactic acid (DLA) and inflammatory cytokines in serum were also measured. Compared with the Control group, Actigen and antibiotics supplemented diets reduced incidence of diarrhea (P < 0.05), with no effect on growth performance. Intestinal morphology revealed that antibiotics decreased (P < 0.01), while Actigen increased the villus height and the ratio of villus height to crypt depth (P < 0.01). PAS staining demonstrated that the goblet cell number was elevated in jejunum of the Actigen fed piglets compared with the Antibiotics group (P < 0.05). In addition, the use of antibiotics decreased the expression of tight junction proteins (P < 0.05), while the use of Actigen increased it (P < 0.05). Accordingly, the intestinal permeability was elevated by antibiotics use, with the increased serum DLA (P < 0.05). Furthermore, Actigen fed piglets had lower serum proinflammatory cytokine TNF-α (P < 0.05) and higher serum anti-inflammatory cytokine IL-10 (P < 0.05). In contrast, antibiotics use led to an increase of serum IL-1β (P < 0.05). Moreover, the expression of TLR4, Myd88, and IKKβ phosphyorlation were enhanced by antibiotics use (P < 0.05), suggesting the activation of TLR4 signaling pathway. However, Actigen supplemented diet had no effect on the TLR4 signaling pathway. In conclusion, compared with the Control group, Actigen supplemented diet had no effects on ADG, ADFI and FCR, but reduced the incidence of diarrhea and mortality to the similar level as the Antibiotics group. Actigen also improved the intestinal morphology and permeability, reduced intestinal inflammatory response compared with the Antibiotics group. These findings suggested the potential application of Actigen in weaned piglets production.