Effects of Selenium-Enriched Lactobacillus plantarum on Production Performance, Egg Selenium Deposition, and Ovarian Antioxidant Function in Laying Hens During the Late Laying Period.

In late-laying hens, the progressive decline in reproductive performance is fundamentally linked to oxidative stress-induced ovarian dysfunction, where conventional dietary selenium (Se) levels often fail to maintain systemic and localized redox homeostasis. The aim of this study was thus to investigate the regulatory effects of supplemental selenium-enriched Lactobacillus plantarum (Se-LP) on production performance, egg quality, Se deposition, and ovarian antioxidant function. A total of 720 hens (63 weeks of age) were randomly assigned to five treatments (8 replicates/group, 18 hens/replicate) and fed either a basal diet (0.275 mg/kg Se) or the basal diet supplemented with 0.1, 0.2, 0.3, or 0.4 mg/kg Se from Se-LP for 8 weeks. Results indicated that dietary supplementation of Se-LP linearly improved the qualified egg rate, egg shape index, eggshell thickness, and Se deposition in eggs (linear, P < 0.05). Se-LP significantly enhanced total antioxidant capacity (T-AOC) and the activities of glutathione peroxidase (GSH-Px) and total superoxide dismutase (T-SOD) in both serum and ovaries (linear, P < 0.05). Se-LP significantly upregulated the mRNA expressions of GPx4, TXNRD1, and TXNRD2, while increasing the transcriptional levels of the key transcription factor Nrf2 in the ovaries (linear, P < 0.05). In summary, dietary supplementation of Se-LP (0.3-0.4 mg/kg) offers a potent nutritional strategy to delay reproductive senescence by reinforcing the Nrf2-mediated antioxidant shield. This not only optimizes eggshell quality and Se-enrichment in commercial production but also extends the functional lifespan of aging laying hens.