Effect of yeast Saccharomyces cerevisiae supplementation on serum antioxidant capacity, mucosal sIgA secretions and gut microbial populations in weaned piglets

This study was conducted to determine the effect of different forms of yeasts Saccharomyces cerevisiae supplementation on serum antioxidant capacity, mucosal secretory immunoglobulin A (sIgA) secretions and gut microbial populations in weaned piglets. A total of 96 piglets weaned at 14 d of age were randomly allotted to 4 dietary treatments: (1) basal diet without yeast (Control); (2) basal diet supplemented with 3.00 g kg−1 live yeast (LY); (3) basal diet supplemented with 2.66 g kg−1 heat-killed whole yeast (HKY); and (4) basal diet supplemented with 3.00 g kg−1 superfine yeast powders (SFY). Each treatment had 4 replicates (pens), with 6 piglets per replicate. The experiment lasted for 3 wk. At d 7 and 21 of the experiment, the samples of serum, mucosa and mesenteric lymph node (MLN) from jejunum, and digesta from the ileum and cecum were collected for determinations. Compared with the Control, dietary SFY supplementation increased serum superoxide dismutase (SOD) activity and lysozyme levels at d 7, and jejunum mucosal slgA secretions at d 21 of the experiment (P<0.05). Dietary LY supplementation increased serum SOD activity and jejunum mucosal slgA secretions, but decreased serum malondialdehyde (MDA) concentration at d 7 and 21 (P<0.05). Piglets fed diets supplemented with LY and SFY had lower pH values and decreased numbers of Escherichia coli in the ileum and cecum contents at d 21 compared with the Control (P<0.05). Moreover, the ratio of Lactobacilli to E. coli in the ileum and cecum contents was increased by dietary LY and SFY supplementations (P<0.05). Collectively, different forms of yeasts, especially LY and SFY, may modulate body antioxidant capacity and enhance the intestinal immunity by regulation of secretions of mucosal sIgA and reduction of pathogenic bacteria colonization, thus improving intestinal health of weaned piglets.