The effects of dietary supplementation with mushroom or selenium enriched mushroom powders on the growth performance and intestinal health of post-weaned pigs

Background: There is an urgent need to identify natural bioactive compounds that can enhance gastrointestinal health and promote pig growth performance in the absence of in-feed medications. The objectives of this study were to: 1) compare the effects of mushroom powder supplemented with inorganic selenium (inSeMP) to mushroom powder enriched with organic selenium (orgSeMP) to pharmacological levels of zinc oxide (ZnO) on growth performance and faecal scores for the first 21 days post-weaning (Period 1); and 2) compare the molecular and microbial effects of inSeMP and orgSeMP in these pigs on day 39 post-weaning (Period 2). Methods In Period 1, pigs (3 pigs/pen; 8 pens/treatment) were assigned to: (1) basal diet (control); (2) basal diet + zinc oxide (ZnO) (3100 mg/kg feed); (3) basal diet + mushroom powder supplemented with inorganic selenium (inSeMP) containing selenium (selenite) content of 0.3 mg/kg feed; (4) basal diet + mushroom powder enriched with organic selenium (orgSeMP) containing selenium (selenocysteine) content of 0.3 mg/kg feed. The inorganic selenium was in the form of sodium selenite and the organic selenium was in the form of selenocysteine. Mushroom powders were included at 6.5 g/kg of feed and contained a β-glucan content of 650 mg/kg. Results In Period 1, there was no effect of diets on average daily gain (ADG) and gain:feed (G:F) ratio. The orgSeMP supplemented pigs had a lower average daily feed intake (ADFI) compared to all other groups. The ZnO supplemented pigs had reduced (P < 0.05) faecal scores compared to the basal and mushroom group, while the orgSeMP supplemented pigs had lower faecal scores compared to the basal group during the 21-day experimental period. In Period 2, there was no effect of diets on ADFI, ADG and G:F ratio. The orgSeMP supplementation increased the caecal abundance of bacterial members of the Firmicutes and Bacteroidetes phylum, including Lactobacillus, Agathobacter, Roseburia and Prevotella and decreased the abundance of Sporobacter compared to the basal group, while inSeMP increased the caecal abundance of Prevotella and decreased the caecal abundance of Sporobacter . Dietary supplementation with inSeMP increased expression of TLR4 and anti-inflammatory cytokine gene IL10 (P < 0.05) and decreased nutrient transporter gene FABP2 (P < 0.05) compared to the orgSeMP group. Conclusion OrgSeMP has potential, as a dietary supplement, to improve gastrointestinal health in pigs through improved faecal scores and modulation of the gastrointestinal microbiota.