The purpose of this study was to evaluate the inhibitory activity of selenium-enriched probiotics against pathogenic Escherichia coli (E. coli) in vitro and in vivo. Escherichia coli was co-cultured in vitro with each probiotic strain individually, and a mixture of the four strains and its population was counted at various time points. We also collected a cell-free culture supernatant (CFCS) of each probiotic strain and the four-strain mix to examine their antibacterial activity, using the cylinder plate method. Results demonstrated that co-culture with probiotics significantly reduced the number of E. coli. The different sizes of the inhibition zones made by each CFCS proved that E. coli was inhibited by the metabolites of the probiotics. In vivo, Kunming mice were allocated to different groups supplemented with selenium-enriched and other probiotics. After 28 days, the mice were inoculated with pathogenic E. coli so that we could compare mortality rates and inspect other indexes of each treatment. The mortality of the group with selenium-enriched probiotics was the lowest. In addition, the organic antioxidant status improved, immunity was fortified, and the internal environment of the intestinal tract was enhanced with selenium-enriched probiotic supplementation. In conclusion, selenium-enriched probiotics can strongly antagonize pathogenic E. coli in vitro and in vivo.

A 35-day experiment was conducted to evaluate the effect of selenium-enriched probiotics (SP) on laying performance, egg quality, egg selenium (Se) content, and egg glutathione peroxidase (GPX) activity. Five hundred 58-week-old Rohman laying hens were randomly allotted to 5 dietary treatments of 100 each. Each treatment had 5 replicates, and each replicate had 5 cages with 4 hens per cage. The SP was supplemented to a corn-soybean-meal basal diet at 3 different levels that supplied total Se at 0.2, 0.5, and 1.0 mg/kg. The basal diet served as a blank control, while the basal diet with supplemental probiotics served as a probiotics control. The results showed that dietary SP supplementation not only increased (p < 0.05) the rate of egg laying, day egg weight, mean egg weight, egg Se content, and egg GPX activity but also decreased (p < 0.05) the feed:egg ratio and egg cholesterol content. The egg Se content was gradually increased (p < 0.05) along with the increasing level of dietary Se. The SP supplementation also slowed down (p < 0.05) the drop of Haugh units (HU) of eggs stored at room temperature. The egg GPX activity had a positive correlation (p < 0.01) with egg Se content and a negative correlation (p < 0.01) with egg HU drop. These results suggested that Se contents, GPX activity, and HU of eggs were affected by the dietary Se level, whereas the egg-laying performance and egg cholesterol content were affected by the dietary probiotics. It was concluded that this SP is an effective feed additive that combines the organic Se benefit for hen and human health with the probiotics benefit for laying hen production performance. It was also suggested that the eggs from hens fed this SP can serve as a nutraceutical food with high Se and low cholesterol contents for both healthy people and patients with hyperlipidemia, fatty liver, or cardiovascular disease.

Supplementation of diet with SY appears to be of more benefit than SS in producing favorable milk with high PUFA and Se concentrations.

No abstract

The expression and activity of selenoenzymes are regulated by Se. In the present study, the effects of different forms and concentrations of Se on the regulation of glutathione peroxidase (GPx) activity and phospholipid hydroperoxide GPx (GPx4) and type I deiodinase (D1) mRNA levels in chicken hepatocytes were evaluated. Primary cultured chicken hepatocyte monolayers derived from male White Leghorn chickens (aged 30 -40 d) were incubated for 24 h with 0 (control), 0·5, 1, 1·5, 2, 3, 4 or 5 mmol/l of Se supplied as DL-selenomethionine (Se-Met), k-selenocarrageenan (Se-Car) or sodium selenite (Na 2 SeO 3 ). Compared with the control, Se significantly increased GPx activity in all the hepatocytes, but the activity was not increased in the hepatocytes treated with 5 mmol/l of Na 2 SeO 3 , with maximal effects being observed at 2 mmol/l of Se-Met or Se-Car and at 1·5 mmol/l of Na 2 SeO 3 , respectively. Significant decreases in GPx4 mRNA levels were observed in all the hepatocytes treated with Se (v. control). The D1 mRNA levels were significantly increased in all the groups treated with Se (v. control), with maximal effects being observed at 1·5 mmol/l of Se-Met and at 0·5 mmol/l of Se-Car or Na 2 SeO 3 , respectively. Se-Met at doses of 1·5 -5 mmol/l had a greater effect on D1 mRNA than Se-Car and Na 2 SeO 3 at equivalent doses. After resulting in a maximal effect, higher Se supplementation led to a dose-dependent reduction in GPx activity and D1 mRNA levels in all the hepatocytes treated with Se. These results suggest that in chicken hepatocytes, the regulations of GPx and D1 by different forms and concentrations of Se vary.Selenium: Glutathione peroxidase activity: Phospholipid hydroperoxide glutathione peroxidase mRNA: Type I deiodinase mRNA