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 sIgA secretions at d 21 of the experiment (P<0.05).  Dietary LY supplementation increased serum SOD activity and jejunum mucosal sIgA 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.

To investigate the effects of a synthetic isoflavone (SI) on meat quality and oxidative stability, 1 500 43-d-old Lingnan yellow male broilers were randomly assigned to five dietary treatments: diets supplemented with 0, 10, 20, 40, or 80 mg SI kg-1, fed ad libitum for a period of 3 wk. After refrigerated storage, a* value of the meat increased with dietary SI supplementation using 10 and 40 mg kg-1 level (P<0.05), L* value decreased (P<0.05), and 40 mg kg-1 increased the pH (P<0.05). Supplementation with SI, at all levels, increased water holding capacity (P<0.05) and decreased lactic acid content of meat (P<0.05). The concentration of malondialdehyde at 72 h decreased linearly (P=0.005) and quadratically (P=0.004) with increasing levels of SI. Dietary SI at 20 and 40 mg kg-1 levels enhanced total superoxide dismutase activity in meat (P<0.05). Meat pH quadratically decreased as the storage time increased (P<0.05), with the highest value at 24 h (P<0.05). Lactic acid and malondialdehyde concentrations of meat increased over time, with value at 96 h being far higher than at earlier times (P<0.05). Supplemental SI linearly and quadratically increased the mRNA abundance of glutathione peroxidase (GPX) (P=0.001 and P=0.002) and catalase (CAT) (P=0.003 and P=0.006) in breast muscle. The results from this study indicate that dietary supplementation with SI can improve meat quality during refrigerated storage by decreasing lipid peroxidation and enhancing oxidative stability and, for male broilers from 43 to 63 d of age, the optimal level of SI was 40 mg kg-1.