Characterization of selenium-enriched Lactiplantibacillus plantarum and its effects on egg selenium deposition and...

Selenium-enriched Lactiplantibacillus plantarum (SEL) is a selenium supplement with potential probiotic properties, yet its characterization and dose-response efficacy in laying hens remain poorly defined. This study aimed to characterize the selenium speciation and nanoparticle properties of a laboratory-prepared SEL product and to establish a dose-response framework for egg selenium biofortification. Multi-method physicochemical characterization confirmed that elemental selenium nanoparticles (SeNPs) constituted 76.54% of total selenium, with an organic biomolecular surface coating, confirming efficient biotransformation of inorganic selenite by L. plantarum GS-3. In the animal trial, 240 Hy-Line Brown laying hens at 22 weeks old were randomly allocated to five treatments, including an unsupplemented control and four graded SEL levels (0.3, 0.6, 1.5, and 3.0 mg Se/kg diet). The animal experiment lasted for 8 weeks. The results showed that SEL supplementation had no significant effect on any production performance (P > 0.05). Eggshell thickness was significantly reduced in SEL-supplemented groups at both weeks 4 and 8 (P < 0.001), possibly reflecting selenium-associated modulation of uterine calcium transport or eggshell mineralization processes; albumen height and Haugh unit were transiently reduced at week 4 but recovered at week 8. Egg selenium content increased linearly with dietary SEL level in both albumen and yolk at weeks 4 and 8 (P < 0.001), with evidence of a deposition plateau in yolk at 1.5 mg Se/kg. These findings provide comprehensive physicochemical characterization of a biogenic SEL product and establish a dose-response framework for selenium biofortification of eggs using selenium-enriched L. plantarum.